yea it can be done. if i remember right. you gotta drop the crossmember a lil to drop the pan. a friend of mine got it done and the motor sounded sweet after it was fixed. i also had a supra that i had the rod bearings replaced with the motor still in the car. didnt take long either.
just make sure you got those torque specs and alot of grease and you should be good.
If you can get your oil pan off then changing the rod bearings in the car is easy. You can also do the main bearings while you're in there although not everyone knows that...and maybe change out the oil pump if you aren't sure of its condition or if the pressure is low. Might as well make it worth it since its going to take you a while to get the pan off.
you can ... but in all honesty it's much easier to pull the engine... why not just pull the engine put it on a stand and do it standing up instead of on your back getting oil dripped on you. What if the rod is trashed? or the crank is trash...? You will have to pull the motor anyways and have to put the crossmember together. You could also replace other seals that are easy to get to when the engine is out.
I believe just taking out the engine would be easier too, however those who don't have access to a engine crane won't be able to go that route.
I was in the same position too, except I finally just went out and bought a crane since they were going to charge me $20 an hour just to rent one. A crane is about $150-300, which isn't all that bad if you plan to work on more than one car.