I fought about this before and probally will again, but I see a few problems with the idea. There are too many variables, trying to drop the tempature of a hot intake about 25lbs of metal, than if your sucessful in doing that now your trying to transfer the cooling effect from the intake to the incoming air charge. First off the air coming through the intake doesn't stay long enough in the intake comparment to be able to have a reduction in its tempature. Now your so called cold air is entering the intake ports of the cylinder head which is still hot.
As I see it an intake isn't a very efficient water/air intercooler even with ice on it. I'm nop arguing the fact that cooler denser air makes more power thats quiet obvious just drive your car in the winter, the the ice on the intake is a placebo effect if you ask me. But hey what it takes to make you go faster wether its real or not, go for it.