This question's answers suggest buying a table saw blade with a flat top grind (FTG). I haven't seen any of these locally, and I happen to have at least one dull carbide-tipped, alternating angled tooth blade, so how can I re-grind this blade to have flat topped teeth?
I happen to have at least one dull carbide-tipped, alternating angled tooth blade
I doubt that it's even possible to create a FTG blade from a ATB blade. You might be able to flatten the tops of the beveled teeth somewhat, so that they're still beveled but leave a flat bottomed kerf, but you'd have to remove a lot of material to do it. Since silicon carbide is among the hardest of materials (it's a 9.5 on the Mohs scale, where diamond is a 10), removing a lot of material isn't going to be easy. Your best bet, if you really want to do it, would be to send it out to a saw blade sharpening service that can do the job right.
I think the right solution, though, is to send your ATB blade out for resharpening as an ATB blade, and buy a blade that was designed to be FTG from the start. Amazon carries FTG blades with prices as low as $16, so it's hard to see much point in paying someone to convert an old blade to FTG and getting a mediocre (at best) substitute for the real thing.
Another good option is to use one of the blades from a stacked dado set. Stacked dado set blades are always flat ground because they're meant to produce flat-bottomed dadoes, and there's no rule that says that you can't use just one of the blades. Choose one of the outer blades, as the outer blades generally have more teeth than the inner "chipper" blades.