I don't like porting heads, but I put a piece of 3/8" fuel hose over the shank of my long carbide burr. I found it useful for using it as a guide to control the cutting end.

If I port another set of heads, I'll try using my mill to do most of the work. I don't know how that will work out, but if I can figure out how to program a port, I wouldn't be doing the hand work as much.