Shouldn't be too hard as long as you get everything back in the right order. I considered this too, but after being told I needed some specialty tools to do it right, I just opted to stick a used one in and call it done.
If I keep my GP long enough to need another trans, then I'll get a TEP and call it done. Rebuilding the most complicated part of a car is NOT something I want to do twice. Not cost or time effective in my book. If I can't be 100% sure I have it right the first time, then I feel it's better left to the pros, and a warranty
Jay