trying to change the altenator on a G20 and it looks like I need to remove half the motor. anyone have any "how to" steps?

It's quite simple. First you need to loosen the nut on the adjustment guide. Then you need to loosen the nut at the bottom of the alternator, which is screwed on a long bolt. Once you get those two items loose, you can adjust the tension on the alternator so you can remove the belt. Once the belt is off, you need to remove the ground/power wires. Now you are ready to completely remove the long bolt at the bottom and take the alternator out. It might be easier to remove the fans also. They remove come out from right to left if facing the front of the car. Just 4 screws hold each fan in place and 1 harness plug for each.

Not all that easy. The bolt that the alternator pivots on can be terribly difficult. Mine was installed with the head about 3" from the frame. Different people have suggested dropping the whole side of the engine by 5-6 inches so you can pull it out from the wheel well or cutting it off and installing the new bolt from the opposite (drivers) side.