time signature question

[Kieren MacMillan]

Hello all,

I am engraving a piece which includes a time signature of 7 dotted sixteenths 
(displayed as a note, not a number). I found the LSR snippet to make the 
denominator a note, but I'm having difficulty getting the correct output. Any 
assistance — especially in the form of existing Scheme functions — would be 
appreciated.

(Trevor: I cc-ed you directly on this because I know you've got experience with 
uncommon rational time signatures…)

Thanks,
Kieren.