I managed to do this job recently without jacking the engine up. I didn't get the sump out from between the engine and front diff, but dropped it far enough to be able to check the oil bolt and change the gasket over. You need to slide the gasket along from the front under the oil pickup tube towards the back.
I read on here someone used cable ties in the bolt holes to hold the gasket in place while repositioning the sump back in place, and I don't think I would have managed it without doing so myself. THink I used about 3 cable ties along each side, and just snipped them before putting that particular bolt back in.
1300 km since doing it a week ago, and no problem yet that I can see.

