ahhh....I'm not sure if there is a way around pulling the engine, I don't see why you would have to but there might be some odd clearance issue I'm not seeing. If you don't it really shouldn't be that bad. Basically unplug everything, take out your shafts, remove the plastic flywheel cover thats connected to the bell housing, turn the engine to gain access and remove each of the flywheel bolts, get a stand under it, unbolt the trans mounts then bada bing. I think the trans-mount thing will be the biggest issue. Because of the way they're angled (up and in) it might be pretty tough to...hmm...come to think of it I think those are going to be a pretty big problem. Picturing it I think you would have to rock the trans to get it off and away from the mounts, and that'd be tough with the engine firmly mounted and not knocking your torque converter around...hmm... Maybe you just have to pull the rear one out and push the trans to the driver side then back to the firewall to clear the front mount..ahh dunno but something tells me GM was nice enough not to force you to pull the engine (or pay for the 12hr remove and replace it calls for) to get the trans. If you do have to pull the engine count on a solid 5 hour job if you read fast and have all your tools. The "book" calls for 12hour remove and replace on the engine. I don't have my chiltons handy so I can't look that up, the only times I pulled the trans was after I pulled the engine. Anyway enough confusing everyone with my double talk, if you have any q'* shoot me a PM.
Stuff got done.