re:Creating Lead Sheets

[Carl Sorensen]

You can have entirely different music expressions in the ChordNames
context than in the Voice context.  You just keep the spacing the same,
and enter your chords in the ChordNames context using the guidelines
from the manual.
http://lilypond.org/doc/v2.2/Documentation/user/out-www/lilypond/A-lead-sheet.html#A%20lead%20sheet
shows how to make the notes separate from the chords.  Click on the last
music example in your browser, and you'll see the lilypond source for
the example.

http://lilypond.org/doc/v2.2/Documentation/user/out-www/lilypond/Chords-mode.html#Chords%20mode
gives full instructions for how to generate more complex chord names,
but all of  the examples on this page show the chords being used to give
notes, rather than chord names.

If you'll use the chord notations as given on the second page listed
above, but put them in the ChordNames context as shown in the first page
listed above, you'll get the fancy chord names.  And then you can put
whatever music you'd like to show up on the staff in the Voice context. 
I think that will give you what you're looking for.

HTH,

Carl Sorensen