ok, finally got this squared away.
there were two problems.
first of all, even though my download of pugsy's mame cheat.zip (from his site) completed normally, it wasn't the right size.
i re-downloaded it, extracted the root zip file which solved the first problem.
the second problem was, i misunderstood Tafoid's comment of "The cheat.zip acts like an additional CHEAT folder as it retains the folder structure it was compressed with." which was stupid on my part. i thought he meant that cheat.zip now had to be placed in its own cheat folder in the mame directory (~/.mame/cheat).
after solving the first problem, i then realized what he meant and placed the cheat file in the mame root directory and i now have cheats working.
thanks for the help & pointers everyone.