Blues/jazz/rubato tempo markings in printed scores

[Joel C. Salomon]

Searching the archives, I found the thread “jazz quantization of
eighths for MIDI”
<http://thread.gmane.org/gmane.comp.gnu.lilypond.devel/17489>, linking
to <http://code.google.com/p/lilypond/issues/detail?id=687>, all
relating to adjusting MIDI output.

Is there a way to *print* a tempo marking for such a rhythm, though?
One score I’ve seen uses a tempo marking that looks like this:

                ⌐3¬
Blues feel (♫ = ♩ ♪)

I was thinking to adapt the technique from
<http://lsr.dsi.unimi.it/LSR/Item?id=574>, but the \note command seems
to support neither beamed notes nor tuplets.  Is there something in
the manual that will make the answer obvious once I understand it, or
is this something difficult to achieve?

—Joel