I ski a Scorpion 130 race boot - I went for an extra tight fit this past year, but started to have problems with hot-spots in the toes after a handful of days. I attempted to fix them via conventional boot stretching, but I think the fitter was stoned the second time he worked them and he pushed out the whole side of the boot instead of the toe box, ruining them.
I suffered for a while, then got together with the shop owner and we agreed to experiment with my boots - I figured I had nothing to lose. He re-shaped the boot shells by cooking them in an oven then pressure-fitting them on a rig designed for the Fisher Vacuum boot line. You quickly stuff in the liners, jump in them, then an air bag is fitted around the hot boot and it is pressurized. The boot is press-fit around your foot, then cools and is now custom-molded. Wicked. He felt that it would work on any boot - just needed a little more temperature. It worked very well and corrected the screwed up push. Unfortunately, my liners were/are fairly sacked out already, so my end fit wasn't absolutely perfect, but it's pretty close - no slop and no pain.
The real key would be to do this with a brand-new pair of boots (or liners). With the shells form-fit to your feet with a new liner, you'd get a 95% fit with the stock thickness of the liner all the way around your feet. Any little foot-shape nuances that the shell fitting didn't get would get taken up by the liner, but liner forming would be minimal instead of having to do the whole job. Could you imagine how awesome the fit would be having a liner whose thickness only had to change a fraction of what it does now?? I'm definitely doing it with my next pair of alpine boots (don't know if I can get away with cooking a telemark boot though...). I see this as the eventual future of boot buying.