Chord names with I, IV, V, etc.

[Geoffrey Prewett]

Hi,

I've recently begun using lilypond to make lead sheets.  The songs I play
have a tendency to get transposed to different keys, depending on the situation,
so I would like to put the meta-chord (or whatever I, ii, IV, V, etc. are
supposed to be called) instead of the chord for a given key.  I assume that
I could do this by creating a custom chordRootNamer function, but I can't
find any examples on how to do that.  Are there any examples or documentation
I can look at?

Thanks,
Geoff Prewett