Depends on what sort of workshop you have.
Basically, remove the mowing deck, then physically position the tractor on it's tail end, pointng vertically upwards. Wedge it securely in this position. This position prevents oil spills, and makes everything accessible.
Remove the rear wheels (which should be clear of the ground if positioned correctly). Disconnect the shift lever, and brake lever. Apply parking brake (now disconnected, but this will slacken the drive belt), unbolt mounting bolts, and remove transaxle.
Not diffcult, but requires a fair degree of physical strength.
phil_saunders(a)bigfoot.com
Phil Saunders, September 2009