Jaybird,
I have succesfully tried that approach before ona few truck parts but have yet needed to try it on my bike, but it takes nerves of steel, lots of trust in the heat dissapating qualities of aluminum,and a bit of luck. With the race that is pressed on exposed < rollers and cage broken off> Use a cutting torch and just shave off the outside edge of the race ,burning a thin flat spot. With the race softened and thinned from the heat, the heat transferring to the aluminum and expanding strecthing the race it will come off relatively easy after it cools back down and aluminum shrinks back to normal but the race is still stretched.
I use this as a last resort when a press and bearing separator is not enough to do the job for a few reasons. 1 you have to be extremely quick and good with a steady hand. Burning steel I believe is at a temparature around 3500 degrees farenhiet when aluminum melts at 1400. Burning a hardened race is a lot different than cutting low carbon structural steel which is what I am used to, you can very easliy knick the aluminum with the torch or spot it up real bad with the slag being thrown from the cutting torch. As I said this is the last resort before before throwing all the involved parts away because you may just as well be doing that any way after trying this.
I have never done this with a steering stem bearing but I thought you might be interested in that.
For a steering stem bearing or any part along the same type of design where I can use a 4"grinder and grind the race paper thin in two spots,and then smack a thicker part of the race where you just ground away from the thin spot and just break it off with a hammer and chisel. This time it takes patience and a steady hand to be able to sit there grinding away at some hardened steel stopping often to inspect your progress closely Which is what I would suggest to J.P. if he trusts his steady hand . Again this is when the press and bearing separator won't cut the mustard or not available