You didn't specify whether it's caused by cold. My toes get kind of numb the first couple of times I wear my boots at the start of the season, but that's before I even get to the mountain so it's not temps. Once my boots and my feet get used to each other again, I'm good for the rest of the season.
If your problem is temps, socks make a HUGE difference. Wear those white cotton sweatsocks and you are screwed. Get some good wool socks. Burton's brand is surprisingly inexpensive and good quality.
If your problem is pressure points, you might benefit from just wearing your boots around the house, first without tightening them.