Tim, Depending if you already have a fixture or not. If you do your wiring is already there. BUT, I would bet that the box does not meet NEC code. A normal celing box will not properly support the fan and the torque of the motor. They sell a kit so you can remove the exsisting box and replace it with an approved box. Try your home center or electrical contractor.
If you don't already have a fixture present, you'll have to install a approved box and wiring. If your not familiar with this type of work, call a skilled contractor.
Ceiling fan manufacturers sell a variety of accessories for sloped and vaulted celings. Try Hunter of Casablanca.