I just did this this past summer and it's not a big deal. A few tips:
1. The manual fails to mention that the transmission disconnects from the bell housing BEFORE being removed. In other words, leave the bell housing attached to the engine and remove the transmission, then remove the bell housing from the engine. There is a seperate set of bolts that are accessible with the trasmission still in place. Removing the transmission with the bell housing still attached to it is either extremely difficult or impossible.
2. You'll most likely need a bearing puller to remove the pilot bearing in the end of the crankshaft. It's a very specialized tool but I finally found one (an entire kit, actually) at a local Pep Boys for $150.
3. If you buy the LUK clutch kit note that the clutch alignment tool included with it is not the right size. I think it's made for the Ram. This makes it too inaccurate in the Viper to align the clutch properly. You'll need a universal clutch alignment tool. $20 or so. Don't try to eye-ball it or you'll spend a month of Sundays trying to figure out why the transmission won't go in that extra 1/2 an inch.
4. That transmission is HEAVY. This isn't a Volkswagen so be very careful and don't try to install or remove it alone unless you have a good transmission jack. Use the safety chains.
5. The consensus on replacement fluid is that you should use what the dealership sells for the Viper. I don't remember the specs but it's listed in the "Viper Fluids" list here on the board. It's expensive at $20 a quart.
6. You may as well install the skip-shift eliminator while you're in there.
I don't remember how much the dealer charges to do this but by the time you buy all the tools, parts and that expensive fluid you're not going to save a lot of money. Do it for the experience though. Besides, you can never have too many tools.
--Rob