which version of FL do you have??
if its 3, good luck...
if its 4, you gotta find the right sounds and then mess with the individual hits (of lets say, the hats.) change the velocities (volume) of some of the hits... by just clicking the boxes alone -- and leaving it like that, they will all be exactly equal in volume -- therefore making it very obvious that theyre not real. mess around with the panning of the hats, as well as all cymbals and toms -- just like you would if they were real drums.
if its 5,open up a new project, then go to "packs" then "FPC." switch out the drums on the new project with the ones you like from "FPC." the drums in FPC are actually real live samples, not electronic techno crap (no offense to anyone -- its just frustrating as F when youre trying to do a rock song on top of straight up techno sounds.) and then use the same panning/volume advice i mentioned for 4.
not familiar with 6, but i imagine its pretty much identical to 5
if you need any more help, feel free to ask away