Put a mic pointing at the table, use a pen and tap it at the prefered tempo. You might wanna use a low cut on that.
Or you could also use a metronome/drumcoputer with an output/headphone jack.
have fun,
greetz,
Does the HD24 have a video output with cut and paste editing? If so you can record a single click then cut and paste it to the quarter notes. That way it is synced up with the beat display and will make editing easier.
If you don't need it synced then a metronome or drum machine would be the best option.
That's a pretty sweet setup. Anyway, I recommend getting a cheap drum machine. Try the pawn shops, and used stores. They are usually full of old drum machines that the rappers didn't scoop up ;-)