How difficult is it to change the door latch on '03 Discovery?

How difficult is it to change the rear door latches on an '03 Discovery?  I am just over the 50k warranty, but Land Rover has agreed to offer parts but not labor.  The dealership is going to charge $400+ for labor.  That's just out of the question for us.  Hoping to do it ourselves.

Are you talking about the rear passanger door or the tail gate?

Rear doors...not tailgate.

Just out of curiosity what is wrong with your's, they normally don't fail?

The automatic locks stopped working a couple of weeks ago.  I took it to the dealership b/c I didn't want to mess with the panel and wires.  I figured I could let them figure out what was wrong with it before I started buying parts for it.  They told me the door latches needed to be replaced.  The guy that explained it to me made it sound like a fairly common problem.  He said you could experience intermittent problems (working then not) for a while.  Then it could completely go, and it could lock in either the open or closed position. 

You might want to consider downloading a Rave CD which has the complete shop manual on your vehicle, it makes it easy to change out the latch assembly.

Thanks for the info.  Where can I find that?