You can do a beat in odd time, but you won't find a lot of rappers that want to put lyrics on it. If you know how to figure out the time signatures and count 5, 6, and 7 (it sounds like you do), chop it up into 4/4 bits; rearrange it until it works. Or, experiment with the 6 section; sometimes that can sound really cool over a 4/4 rhythm underneath (think Led Zeppelin's "Kashmir"). Beef-up your drums with your own samples to give your loop or sequence tonal unity.
GJ
---------- Post added at 06:27 PM ---------- Previous post was at 06:20 PM ----------
Ha. Just saw bandcoach's post (squeeked-in ahead of me!), which gave me an idea-- If all of the parts are from the same song, I'm assuming they are at the same tempo (but different time signatures in different measures?)... If you add it all up (top numbers/pulse), you get 18-- which could work to two measures of 4/4 and a measure of two (or depending on how it's played and the tempo-- two measures of 8/8 and a measure of 2/8; or, or, you get the idea). Anyway, you can fit that over a repeating 4/4 / "four on the floor" beat a la King Crimson and it might be pretty sweet.
GJ