How should I cook a ham bone for chili?
If you're going to simmer your chili for a long time, just throw it in there.  If you made stock with it, you'd still be just simmering the bone for a long time to extract the same flavors.  (I'm not advocating not using stock here, just that I wouldn't make stock for the sole purpose of getting flavor out of the bone.  Use the stock you would otherwise.).

Simmer four plus hours and then pull the bone out, tap the meat off, and enjoy the chili (although I like to cool chili down, put it in the fridge, and eat it the next day better).

If you're going to make the stock with it though, @Cos definitely has the right idea with the pressure cooker.