The graphism for the glissando has already been explained by Mike, but the acoustic result is very unsatisfactory.
In the vast majority of the cases you can have a better result by choosing "white keys".
If the pedal configuration is odd, then probably the only way to have a good result is to use a hidden staff with an arpeggio plugin, like here:
!NoteWorthyComposer(2.751)
|Editor|ActiveStaff:2|CaretIndex:1|CaretPos:-1
|SongInfo|Title:"Toccata"|Author:"Susann McDonald (1935)"|Lyricist:"(approssimazione per celtica)"|Copyright1:""|Copyright2:""
|PgSetup|StaffSize:16|Zoom:4|TitlePage:Y|JustifyVertically:Y|PrintSystemSepMark:N|ExtendLastSystem:N|DurationPadding:Y|PageNumbers:0|StaffLabels:None|BarNumbers:Plain|StartingBar:1
|Font|Style:StaffItalic|Typeface:"Times New Roman"|Size:10|Bold:Y|Italic:Y|CharSet:0
|Font|Style:StaffBold|Typeface:"Times New Roman"|Size:8|Bold:Y|Italic:N|CharSet:0
|Font|Style:StaffLyric|Typeface:"Times New Roman"|Size:7|Bold:N|Italic:N|CharSet:0
|Font|Style:PageTitleText|Typeface:"Times New Roman"|Size:24|Bold:Y|Italic:N|CharSet:0
|Font|Style:PageText|Typeface:"Times New Roman"|Size:12|Bold:N|Italic:N|CharSet:0
|Font|Style:PageSmallText|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User1|Typeface:"MusikDingsSans"|Size:16|Bold:N|Italic:N|CharSet:0
|Font|Style:User2|Typeface:"MusikTextEuroSans"|Size:10|Bold:N|Italic:N|CharSet:0
|Font|Style:User3|Typeface:"MusikTextEuroSans"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User4|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User5|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|Font|Style:User6|Typeface:"Times New Roman"|Size:8|Bold:N|Italic:N|CharSet:0
|PgMargins|Left:1.27|Top:1.27|Right:1.27|Bottom:2.00|Mirror:N
|AddStaff|Name:"Extra 1"|Group:"Standard"
|StaffProperties|EndingBar:Open (hidden)|Visible:Y|BoundaryTop:15|BoundaryBottom:10|Lines:5|WithNextStaff:Brace,ConnectBars,Layer|Color:Default
|StaffProperties|Muted:N|Volume:127|StereoPan:64|Device:0|Channel:3
|StaffInstrument|Name:"Harp"|Patch:46|Trans:0|DynVel:10,30,45,60,75,92,108,127
|Clef|Type:Treble
|Key|Signature:Bb,Eb|Tonic:B
|TimeSig|Signature:2/4
|Dynamic|Style:mp|Pos:-9|Visibility:Never
|Rest|Dur:8th|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|Dir:down|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|Bar
|Rest|Dur:8th|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|Dir:down|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|Bar
|Rest|Dur:8th|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|Dir:down|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|Bar
|Rest|Dur:8th|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|Dir:down|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|User|Arpeggio.ms|Pos:-3|Rate:128|ForceArrow:Y|Visibility:Never
|Chord|Dur:8th|Pos:-9,-8,-7,-5,-4,-2,-1,0,2,3,5,6,7,9,10,12|Opts:Stem=Up,Muted|Visibility:Never
|Bar|SysBreak:Y
|AddStaff|Name:"Right hand"|Label:"Harp"|Group:"Standard"
|StaffProperties|EndingBar:Open (hidden)|Visible:Y|BoundaryTop:15|BoundaryBottom:10|Lines:5|WithNextStaff:Brace,ConnectBars|Color:Default
|StaffProperties|Muted:N|Volume:127|StereoPan:64|Device:0|Channel:1
|StaffInstrument|Name:"Harp"|Patch:46|Trans:0|DynVel:10,30,45,60,75,92,108,127
|Clef|Type:Treble
|Key|Signature:Bb,Eb|Tonic:B
|Tempo|Tempo:78|Pos:9.5
|TimeSig|Signature:2/4
|Dynamic|Style:f|Pos:-10
|Rest|Dur:8th
|Spacer|Width:175
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Text|Text:"( )"|Font:PageText|Pos:11.5|Justify:Center|Placement:AtNextNote
|Note|Dur:8th|Pos:12|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th,Grace|Pos:12|Opts:StemLength=0,Muted|Visibility:Never
|Bar
|Rest|Dur:8th
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Text|Text:"( )"|Font:PageText|Pos:11.5|Justify:Center|Placement:AtNextNote
|Note|Dur:8th|Pos:12|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th,Grace|Pos:12|Opts:StemLength=0,Muted|Visibility:Never
|Bar
|Rest|Dur:8th
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Text|Text:"( )"|Font:PageText|Pos:11.5|Justify:Center|Placement:AtNextNote
|Note|Dur:8th|Pos:12|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th,Grace|Pos:12|Opts:StemLength=0,Muted|Visibility:Never
|Bar
|Rest|Dur:8th
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Text|Text:"( )"|Font:PageText|Pos:11.5|Justify:Center|Placement:AtNextNote
|Note|Dur:8th|Pos:12|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th|Pos:-9|Opts:StemLength=0,Muted
|Spacer|Width:300
|User|Glissando.ms|Pos:-10|Text:
|Note|Dur:8th,Grace|Pos:12|Opts:StemLength=0,Muted|Visibility:Never
|Bar
|AddStaff|Name:"Extra 2"|Group:"Standard"
|StaffProperties|EndingBar:Open (hidden)|Visible:Y|BoundaryTop:10|BoundaryBottom:13|Lines:5|WithNextStaff:Layer|Color:Default
|StaffProperties|Muted:N|Volume:127|StereoPan:64|Device:0|Channel:4
|StaffInstrument|Name:"Harp"|Patch:46|Trans:0|DynVel:10,30,45,60,75,92,108,127
|Clef|Type:Bass
|Key|Signature:Bb,Eb|Tonic:B
|TimeSig|Signature:2/4
|Dynamic|Style:f|Pos:-9|Visibility:Never
|Rest|Dur:Half|Visibility:Never
|Bar
|Rest|Dur:Half|Visibility:Never
|Bar
|Rest|Dur:Half|Visibility:Never
|Bar
|Rest|Dur:Half|Visibility:Never
|Bar
|AddStaff|Name:"Left hand"|Group:"Standard"
|StaffProperties|EndingBar:Open (hidden)|Visible:Y|BoundaryTop:10|BoundaryBottom:13|Lines:5|WithNextStaff:Brace,ConnectBars|Color:Default
|StaffProperties|Muted:N|Volume:127|StereoPan:64|Device:0|Channel:2
|StaffInstrument|Name:"Harp"|Patch:46|Trans:0|DynVel:10,30,45,60,75,92,108,127
|Clef|Type:Bass
|Key|Signature:Bb,Eb|Tonic:B
|TimeSig|Signature:2/4
|Dynamic|Style:f|Pos:-15|Visibility:Never
|Chord|Dur:4th|Pos:-11,-4|Opts:Stem=Up
|Rest|Dur:4th
|Bar
|Chord|Dur:4th|Pos:-7,0|Opts:Stem=Up
|Rest|Dur:4th
|Bar
|Chord|Dur:4th|Pos:-6,1|Opts:Stem=Up
|Rest|Dur:4th
|Bar
|Chord|Dur:4th|Pos:-7,0|Opts:Stem=Up
|Rest|Dur:4th
|Bar
!NoteWorthyComposer-End
Then there is this problem, too:
Regarding the cross-staff beams, you can look at this plugin