Well, I think the first answer was probably the best way to do it...
You may be able to lift the motor enough to get the oil pan off...just undo the motor mounts, loosen the transmission bolts, and remove the drive shaft (you still need to plug the tail or you will end up replacing your tranny fluid) and jack up the motor.
You're limited with space to work like that but it can be done. The valve cover will probably contact the firewall in this process so you might have to remove that to give yourself more room (not much, but more). Or you could remove the transmission bolts, jack the engine up and slide it forward (remove rad) so that the head and VC clear the firewall.
Maybe get a set of ramps and drive the front end up on them before doing anything...but it needs to be running to do that or have a winch to haul it up.
That's why the first answer would work much better...just haul out the engine and transmission in one piece and flip the engine over. That's actually what I did to change the oil pan gasket...but, of course, I had the cab off so it was just a matter of getting a forklift to do the heavy lifting.