I had this problem with another of my vehicles. long story short, my alternator pulley was worn out believe it or not. I had tried to take a piece of sandpaper and scuff the glaze off the pulley, that worked for a couple weeks but the squealing came back. I went as far as taking a chissel and putting little ribs in the pulley to give it grip and that did work but I had ordered a new pulley and once I installed it, never again did my belt squeal. So either try patching it like I did, or just find which pulley is worn or glazed the most and replace it. My bet would be the alternator pulley becuase for one, it has the least ammout of contact area with the belt and it also has a considerable load on it when it's charging. Hope this helps.
__________________ Ben Toppi
'01 Ford Police Interceptor - Daily driver
'04 Ford Mustang GT, black, 5 speed, 40 series flows, o/r H-pipe, bbk intake, SCT dyno tune, ZEX wet nitrous 125shot  , MGW short throw shifter, FRPP aluminum driveshaft, Black Bullitt deep dish wheels with 270/45/17's up front and 315/35/17's out back. Goodyear Eagle F1GSD3's. BBK LCA's. Mach1 grill and assorted stainless accessories - My toy
Dyno #'s = 325hp and 420ft/lbs 
1/4 mile= 13.1@110mph w/2.1 60 ft street tires  |