How to replace accessory serpentine belt on 1996 Riviera

The supercharged 3800 engine uses two accessory drive belts. The outer belt drives the supercharger. The inner belt drives the generator, power steering pump, coolant pump and air conditioning compressor. All driven accessories are rigidly mounted to the engine. Drive belt tension is maintained by the spring loaded belt tensioner. Each belt has its own tensioner.
Remove: Place a jack with a block of wood on it under oil pan to support engine. Caution : Be sure the wood block extends past the width of the oil pan to avoid damage. 
Torque axis engine mount bolt where it connects the mount to the engine mounting bracket. 
Electrical connector from crank sensor. 
Engine mounting bracket lower stud and lower engine to allow stud to clear frame rail. 
Raise engine and reinstall bolt into torque axis mount. Lower engine to allow spacer to be removed. 
Belt(s)

Istalling: Belt. 
Spacer. Remove bolt from torque axis bracket and lower engine. 
Electrical connector to crank sensor. 
Mounting bracket stud. 
Raise engine and install torque axis mount bolt. 
Tighten bolt to 87 Nm (52 lb. ft.) 

Good luck and hope this helps.