I have done the Alt belt and PS/AC belt at least 3 times on my P5 and once on a friend's MSP.
It is pretty easy, the hardest part, IIRC, is breaking loose the alternator. It still is not hard, but I am pretty sure it can only be done from under the car. Taking off the cruise control bolts, I think there are 3 of them, and putting it out of the way might help with the Alt bolts.
I don't have a how to, but I could probably make up one quickly.
1. You have to take the AC/PS belt off anyway, so might as well replace both belts.
2. It is probably recommended to replace the tensioners to, although, I only have done this once or twice.
3. Jack up the car, and do all the safety stuff involved with that and working on a car, such as floor jacks, neg battery cable.
4. IIRC, you will need a:
10mm wrench or socket for the 2 tensioner bolts, and the PS tensioner lock bolt. If using a wrench, having a ratcheting wrench one will help a lot.
12mm wrench or socket for the Alt tensioner lock bolt, and the PS bolt to the motor. If using a wrench, having a ratcheting wrench one will help a lot.
14mm socket with an extension for the Alt bolt to the motor. This is the one that is hard to break loose.
5. Break loose the PS to motor bolt, you do not need to take it off, just loosen it a few turns.
6. Break the locking bolt on the PS tensioner, but don't take it off. Just break it loose.
7. Then loosen the tensioner bolt a crap load of times. As you loosen the bolt, push the PS pump toward the rear of the car, this will loosen the tension of the belt. You might need to loosen the bolt to the motor a little more if it doesn't move, or push it harder.
8. Remove the PS/AC belt.
9. Repeat steps 5-8, but for the Alt instead of PS pump. Also, as you are loosening the Alt tensioner, you should push it up and forward IIRC. This is kind of hard, I guess because of the location, but it will move eventually.
10. Optional* replace tensioner bolts and lock bolts. Pay attention or take a picture of how they are on before removing them, it will make it easier to put new ones on.
11. Put new Alt belt on.
12. Push the Alt down and toward the rear of the car to add tension to the belt, this will make it easier and quicker to adjust the tensioner bolt.
13. Tighten the Alt tensioner bolt until desired tension has been met. Start off by hand to make it quicker.
14. Tighten Alt tensioner lock bolt.
15. Tighten Alt to motor bolt.
16. Repeat steps 11- 15, but do it to the power steering pump. Also, after you have the PS/AC belt on, you will want to pull the pump up and forward to reduce the slack, this will make it easier and quicker to adjust the tensioner bolts.
17. Wrap everything up, put the cruise control back if you removed it.
This was just off of memory, so I might have gotten somethings wrong, if anyone notices that I am missing anything let me know, and I will correct it.
