Try cleaning your belt on both sides with a small wire brush/cleaning brush while the motor is on (be careful of the clutch fan, and watch your fingers in general).
Then when you're done that, rub a 1'' wide dab of dialectic grease on both sides of the belt in one spot.
I read this somewhere else on JF. Apparently dirt on the belt + cold days usually results in a squeak. In my case it has worked and cured squeal for long periods of time.
'96 Laredo Build Thread - http://www.jeepforum.com/forum/f197/zjmtls-project-thread-daily-driver-weekend-getaway-vehicle-1360544/