automatic "note-as-denominator" time signatures?

[Kieren MacMillan]

Hi all,

Can the snippet

  <http://lsr.dsi.unimi.it/LSR/Snippet?id=554>

be made into an automatic callback, instead of requiring the creation  
of a markup each time? i.e., I would love to be able to say something  
like

  \useNoteDenominators

or

  \override TimeSignature #'denominator-style = #'note

and have all denominators be output as notes (rather than numbers).

Thanks for any hints/links,
Kieren.