Hallo Christa,
da ich auch nicht genau weiß,
was Du erreichen möchtest, hier ein (unvollständiger) Überblick.
Unvollständig deshalb weil ich manches mögliche Feature als unwahrscheinlich betrachtet und deshalb nicht dargestellt habe.
Für einige Möglichkeiten braucht man allerdings eine neuere devel-version.
Eine
einzelne Hilfslinie anzusprechen ist mir allerdings nicht gelungen.
Erklärungen im file, ansonsten frag.

\version "2.17.1"
\paper {
indent = 80
}
\header {
title = "Tweaking LedgerLineSpanner"
subtitle = "\\startStaff and \\stopStaff is mostly required to insert the relevant commands."
subsubtitle = \markup \center-column {
"In all examples the first and the last ledger-line/note/chord isn't changed."
"Some examples needs a newer devel-version."
\vspace #4
}
}
% changing thickness
% works with 2.14.2
\relative c' {
\set Staff.instrumentName = \markup \column { "changing thickness" "works with 2.14.2" }
g,4
\startStaff
\override Staff.StaffSymbol #'ledger-line-thickness = #'(0.5 . 0.4)
\stopStaff
c e b' c'' e
\startStaff
\revert Staff.StaffSymbol #'ledger-line-thickness
\stopStaff
g
}
% changing the length
% works with 2.14.2
\relative c' {
\set Staff.instrumentName = \markup \column { "changing the length " "works with 2.14.2" }
g,4
\startStaff
\override Staff.LedgerLineSpanner #'length-fraction = #1.25
\stopStaff
c e b' c'' e
\startStaff
\revert Staff.LedgerLineSpanner #'length-fraction
\stopStaff
g
}
% adding extra-ledger-lines
% newer devel-version requiered!
\relative c' {
\set Staff.instrumentName = \markup \column { "adding extra-ledger-lines" "newer devel-version requiered! " }
g,4
\startStaff
\override Staff.StaffSymbol #'ledger-extra = #2
\stopStaff
c e b' c'' e
\startStaff
\revert Staff.StaffSymbol #'ledger-extra
\stopStaff
g
}
% changing the vertical positions
% newer devel-version requiered!
\relative c' {
\set Staff.instrumentName = \markup \column { "changing the vertical positions" "newer devel-version requiered! " }
g,4
\startStaff
\override Staff.StaffSymbol #'ledger-positions = #'(-5 -3 0 )
\stopStaff
c e b' c'' e
\startStaff
\revert Staff.StaffSymbol #'ledger-positions
\stopStaff
g
}
% changing the vertical positions and adding some more
% newer devel-version requiered!
\relative c' {
\set Staff.instrumentName = \markup \column { "changing the vertical positions" "and adding some more." "newer devel-version requiered! " }
g,4
\startStaff
\override Staff.StaffSymbol #'ledger-positions = #'(-5 -4 -3 -2 0 )
\stopStaff
c e b' c'' e
\startStaff
\revert Staff.StaffSymbol #'ledger-positions
\stopStaff
g
}
\markup \vspace #4
\relative c' {
\set Staff.instrumentName = \markup \column {
"other approach to shorten a ledger-line"
\line { "via" \fontsize #-3 \italic "tweaking NoteHead 'X-extent." }
"works with 2.14.2."
\italic \fontsize #-3 "tweakink 'stem-attachment"
"and overriding"
\fontsize #-3 \italic "'minimum-length-fraction of LedgerLineSpanner "
"is requiered, too "
}
<g''' e c>
\once \override NoteHead #'X-extent = #'(-0.1 . 0.2)
\once \override NoteHead #'stem-attachment = #'(0.1 . 0.2)
\startStaff
\once \override Staff.LedgerLineSpanner #'minimum-length-fraction = #1.8
\stopStaff
<g e c>
<g e c>
}
Gruß,
Harm