You'll probably want to A) put kick, snare and each overhead on seperate tracks which is the best idea... or B) get a good mix with your remaining four tracks and attempt to bounce your drums down to 2 tracks to make space or C) Get a good mix off of a board and feed it into 2 channels. IMHO, A is best, followed by B. You will need some sort of preamp for each.
For best overhead mic sound, both mics should be the same distance from the snare (use a tape measure), with the snare and kick centered in the middle when both mics are panned hard left and right. If those mics are omni pattern you may have to change your approach a little. You can get some good thump out of the kick by compressing it some on the way in and maybe cutting a little around the 315hz area, maybe alot. The snare can be ugly if not mic'ed, eq'ed, and tuned properly. Mic it with the hats in the null area of the mic. There will be much bleed and the overheads will get hats, too. If the overheads get enough snare, you can choose not to use the snare track, and your phase relationship will improve somewhat, hopefully. Or, reverse the phase and put it on the bottom of the snare for a little bit of snare sound. YMMV.
The overheads should be high enough to be above the parrallel plane of the cymbals or they might sound wishy washy. Ususally slightly above and behind the drummers head, pointing at the toms will suffice. Again, use a tape measure after you have them at 90 degree angles. Same distance from same spot on snare.
