Well, not *really* possible, but you can chord step record with the 3/4 style and then chord step record the part of the songs with the 4/4 style and splice it in Cubase/Logic/ etc?
Interesting though, because the Genos 2 and PSRA5000 can do mixed time signatures in a single style; so in theory you *can* chord step record a song that's 3/4 and 4/4 if you put them both in a single style (but different variations) and then render it out.
Mark