You could mic the drums up with two mics but that could actually pose more problems than is worth it. I have recorded drums through one mike before and gotten 'reasonable' results. You need to put the mic very low down (maybe 1 ft off the floor) directly on front of the kit. This will pick up the bass waves more so than the cymbals which can really make the mix tinny. You will have to experiment with a number of takes with and without backing music to get the right distance from the kit, also the accoustics of the room will impact on the overall sound (a smaller practice room would help - or if you are doing it in a home garage, move some matresses up against the walls to reduce echo). This leaves you with one keyboard track and two guitar tracks. You need two guitar tracks for counter melodies and lead (if you have any). Hope that helps.