Removing the belt from the Cadillac Seville may require a serpentine belt removal tool. Using the 1/2 size, rotate the tensioner pulley to relieve tension from the belt. Slip the belt off of the closest pulley you can easily reach. Slowly release the tensioner pulley and being careful not to release it to fast.
After you have removed the old belt check all of the pulleys and make sure none of them are damage and are free of any fluids or debris.
To install the new serpentine belt, using the diagram above, route the belt around all of the pulleys and leave the tensioner for last. Keep tension on the belt with your hand and rotate the tensioner again enough to slip the new belt back on.
Inspect your belt again and make sure it on correctly before starting your vehicle.