It would more likely increase the fuel requirement and decrease mileage...but it is unlikely to do anything at all unless you are having severe operating problems from lean conditions (frying plugs, etc.). You could also have adverse affects from any direct air stream that skewed the pressure function of the sensor. I don't recommend it, and it is likely a waste of your time, but feel free to experiment. Please note that changes in the extension harness length can alter the readings and could also have unexpected effects.
If your engine is overheating, your problem lies elsewhere and needs to be addressed differently. If you suffer from the collection of heat inside the body (hot gas cap, seat, etc.) changing the fuel mixture is unlikely to address the root cause of the problem...and would be more readily accomplished with something like a Power Commander anyway.
