I wouldn't wedge anything in between the rotor to keep it from moving. It puts a lot of strain on it and you risk warping it under that kind of torque. Just have someone riding the brakes so you can break that sucker loose. Air tools are ideal but a breaker bar will work if they aren't too tight. Mine came off no worries when I did both of my axles h: but I have heard some real horror stories about trying to get the frozen nuts loose.

If you are replacing your intermediate shaft or passengers side axle, you need to drain the tranny fluid. It is probably a good practice to replace the fluid when you do an axle replacement anyway.