IMHO, if you're mechanically inclined and careful, taking the trans apart and splitting the case to replace the input shaft and seal is not a big deal. Just be sure to not disturb the gears/shafts any more than necessary. When splitting the case, remove the passengers side (big rubber mallet on bell housing to knock it off after all bolts removed, look for hidden ones) leaving the drivers side lying on the workbench with all the inards in place. When putting the the halfs of the case back together, just be sure to place the top half on carefully that the front output shaft goes thru the seal straight and doesn't knock off the spring inside the lip causing another leak. I will be doing this job myself, again, this weekend.
BTW, Gloyale writeup referenced earlier is pretty good. He covered most of the gottchas. Just don't use too much sealant on the case or pieces can break off eventually and clog oil passages and cause problems (ask me how I know).
Edited by rallynutdon, 16 January 2013 - 01:46 PM.