oil pan removal

ive been trying to remove the oil pan on my 1990 jimmy with the engine still in the vehicle, It doesnt seem to be working.....ive heard that if you jack up the motor and put wood in between the mounts it should be enough clearance but it doesnt seem to be working. Is this the right way to go about it or does the motor need to be pulled? any help would be appreciated.

Geez, I think you've already answered your own question. You have to create enough clearance to get it past the oil sump.