It's going to be pretty tough to paint it while it's in the car. I have heard of guys "touching-up" their engine paint while in the car. I would take the front of the motor apart; alternator, fan, power steering pump (if equipped), etc. Then tape off everything and anything that you don't want to paint. The key is to get the motor absolutely clean; anywhere that you paint over grease or dirt, the paint will not stick and you will be disappointed. Try brushes, degreaser, and a final wipe with brake-kleen to get the oil off. Take your time and be patient. Good Luck!