I would let the shop do it if they are competant and have done diesel VWs
before.  You need a special dial indicator setup, and two other small pieces
of steel (one to lock the pump gear and the other to lock the cam).  All
these timing pieces new will set you back around $100 or maybe a little more.
 Add to that the price of the timing belt and $200 isn't that much more.  
Plus if you have a problem you can take it back to the shop (getting the
timing just right with that dial indicator takes practice to get right every
time).  The diesel engine is interferance (sp) engine so if the belt is off a
couple of teeth you could damage the engine if it started.  Better to leave
it to the pros.
Hope this helps you.


Ken Wilford
Van-Again
John 3:16
http://www.vanagain.com
Office: (856)-765-1583
Fax: (856)-327-2242