This works real well for me sometimes.
Bus the drums and get a decent mix on the drum sounds that you have. Assign the bus to the main mix. Take the bus outs (do not insert) on the board to a stereo compressor and squash the crap out of it. Like a -10 or higher threshold and a ratio of 20.1 or something close. (no fear) Set the attack at about 20ms or so and the release should be quicker than the attack in most cases. Return the compressors signal into a pair of channels on the board.
Now. Assign this highly compressed version on the drums to the main mix and bring it up to just under the original sound. Tuck it right underneath. At this point you start to tweak and for that you are on your own. If the bass is a little flabby an uninteresting you can add the bass in with this process and it can help tighten all the elements of the rhythm section right up!
Cheers
Adam
