How hard it is depends on the grooving iron you get.
I got a cheap version, and when I was working over my XMLs, it was always cooling the blade down.
The big $ ones cut it like butter though, cause they dump a LOT of heat into the blades.
Of course people have used everything from skill saws, chain saws, routers, etc. to groove their tires.
Search pirate on this one. TONS of info, and even decent pictures of hawgs that have been cut up.