Go to the Harley shop and get a service manual and a belt tension gauge. You also need a torque wrench. It is an easy adjustment, and certainly nothing I would ever pay a dealer 75 or 80 an hour to do.
Adjusting the belt isn't rocket science, go get yourself a manual first. CLYMER harley repair manuals are pretty good, you can find them on www.amazon.com , do a search. It took me less than 15 mins to set up the belt, the critical part is the rear wheel alignment, if it doesn't line up properly, you can wear the drive belt in no time.
Good luck!