As I understand it, the issue is with the oil pump pick-up. You can't get the pan low enough to be able to draw it back because of the crossmember. So, at the very least, the motor has to UP. Maybe by removing the Turbo, Trans, and tipping it enough you can get in there and unbolt that pick-up so you could sneak the pan out.
BUT, the real reason to pull the motor is so you can invert it Anyway... The sealant can't be contaminated with the seeping oil that runs down the inside walls of the block so, when upside down, you eliminate that possibility.
IF doing it with the Trans out was in ANY way faster or better, that's what they'd be doing at the dealerships. They Don't, they pull it & invert it because it's Not a job you'd want to have to redo because of a leak...