best epoxy is just the 2 part you mix and apply, comes in like a syringe. I have also used jb weld before in a pinch.
the old hot grips are pretty good.
the thing is when you add hooks, knobs or whatever to the bars, they act as heat sinks and cool off the bars quicker making your grips less warm.
the wrap on style grip wamers of arctic cat sleds and such are a better design and work very well, a crafty guy could adapt those and get the best of both worlds and you dont have to worry about cutting the grip element wires going thru the ends of the grips. You just use motorcycle/atv grips, these you can slip right over the wrap on elements with the air compressor method Pro116 mentioned, be sure to get atv grips though, the atv are both the same size, the dirtbike model ones have one grip larger diameter to go over the twist thortlle tube.