no. just run the heater on with the hood open when you are lining up waiting to be next to stage. you don't want to be idling or revving. you want the engine to cool down. if you have one of those portable fans that can plug into the lighter plug without draining your battery too much...or plug it into a buddy's car lined up beside you who isn't running...even better...blow it over the engine bay and coolant.
icebags can be put on you instead of your IM...but if you want to put it over the IM's coolant ducts, that's ok too but it's not going to cool the engine down. the IM itself may not heat soak as much and that's about it.