belt squeal

Have any of you guys had a belt squeal from the belt being too loose? I got a new belt and installed it but i dont have the spring loaded tensioner because i have a powerdyne supercharger, the tensioner on my setup is basically a pulley that is on a slot it can be adjusted up or down. The problem is i cant push the pulley back into its original position so the belt is a bit loose and squeals upon start up. What should i do?