With the New MAF sensors the IAT sensor is apart of that. So it will never see the temp drop from the methanol because you cannot spray through a MAF sensor. Older GM vehicles you could just relocate the IAT sensor to after the Alcohol injector then it could see the change in temps.
You can however still relocate the IAT with the following modification. You will have to extend the harness to get it after the alcohol injection nozzle for it to work. You can skip the step of modifiying the stock IAT sensor sence the Alcohol injection will do the temp drop for you.
IAT's should be around the ambient air temp or lower with the alcohol injection, I could sometimes see 70F on a 100 degree day.
Reduce LS2 Heatsoak - LS2 IAT Relocate