....where the drive shaft connects to the transmission?

*I'm not talking about the rear main seal

Is your jeep 2wd? if so then i think it is the same as doing the seal on the t-case no need to pull the tranny. Here is a write up hope this helps

http://www.go.jeep-xj.info/HowtoTCseal.htm

Nope.

2WD - pull driveshaft, pull seal. Clean seal bore. Coat outside shell of new seal with a bit of RTV black, drive seal into place. Clean slip yoke (use emery if necessary,) lube slip yoke (wipe some clean transmission lube onto it) and reinstall.

4WD - Pull driveshafts, pull transfer case. Pull seal. Clean seal bore. &c. Clean tcase input shaft (use emery if needed.) Might be a good idea to change tcase input seal and tcase rear output seal while you've got it down... Lube tcase input with transmission lube, reinstall transfer case. Lube slip yoke with Dexron ATF, reinstall rear driveshaft. Reinstall front driveshaft.

Probably an hour for 2WD, if you're thorough. Maybe 2-3 for 4WD - if you're thorough.

where the drive shaft connects to the transfer case? i just got in from replacing the rear one in mine. took maybe 5 mins?? probably longer if your oil slinger won't budge. mine is 4wd.