i've tried to explain this on another post
Its Finally Starting !
but it is possible to figure out how much to move the pitch slider to change the tempo of a track by 1 bpm exactly, so unless your tunes are written at say 145.5 or .7 etc you can just sync the bpms and you're away. This really does work i was taught the method by a mate of mine who plays psy trance and only uses cd's. He doesn't really bother beatmixing at all now and niether did i when i was playing with his decks. A quick listen everynow and then just to check it's not drifting (which it does very occasionally) but that's it
obviously i'd encourage learning how to beatmix anyway