It's pretty easy, but you have to remove some bits and bobs. Step one, remove the chrome instrument cluster on the tank. Three normal hex bolts, the chrome ones. Carefully tip it over to the left (or right, I'm not the boss of you), peel back the rubber around the wires surrounding the connector and push the bit on the connector that loosens it and pull it off. Then lift the instruments off the bike completely. Be a bit careful, the rubber on the edge can come off and then you'll scrape the heck out of the tank if unlucky.
Once you have that out of the way, open two bolts holding the tank down next to the keylock. Edit: forgot the bearclaw, that comes next. One bolt in the front end - untighten, then slide the bearclaw forward and it will come off. Then lift the tank. On the right side of the bike, above the engine, you'll find a stick to support the tank in the upright position. From there, it's a doddle - follow the wire for the heated grip to the relay it is attached to and pull it out of the socket. Then extract all the wires and stuff inside the handlebars (you'll have to take off the grips obviously) if you want it all gone.
I think you do need to remove the seat, but not 100% sure. Either way, that's simple - one bolt behind it (same size as the three holding the instruments down) and two larger ones diagonally behind and under the seat, next to where the shocks mount up top. Remove bolts, lift seat. This is good to know anyway since your battery and fuses are under there.
Personally I might get different heated grips later on myself but may try to just splice into the existing relay and control, ugly tho the box may be on the handlebars.