Thanks guys!
I actually meant freeze, not heat (I was still thinking about my recent rear wheel bearing replacement and mounting the inner race of that bearing to the axle spindle).
I was able to fit the outer races of the two bearings (inner and outer) into the hub after a few hours of keeping the bearings in the freezer (some tapping was still required). Luckily, I have this gigantic socket wrench set (3/4" drive), that has been most handy for tapping in/out bearings and seals of various sizes over the years. Probably the only thing I'd trust Chinese tools for. I'm currently waiting for the gasket shellac to dry on the inner seal before I tap it in.
Although I'd re-packed the front wheel bearings last year, I hadn't really taken off the hubs since I'd bought the car (I'd only re-packed the outer bearing, essentially). Well, on removal of the hub this evening, I saw the worst kind of crud coming out of the inner bearing. I've never seen grease turn into stuff like this. There were solid greasy flakes coming out of there. I'm not sure if this was the cause of my high-speed squeel, but I'm glad to have done this.