The grip heater is part of the grip, so you don't want to expand the grip too much for fear of breaking the heater wires. You do want to keep heated grips, right?
The good news is Yammy didn't use much glue. Remove bar end and have an air compressor with a blow-off nozzle, preferably with a tube you can insert between the grip end and the throttle tube. Remove two screws that hold the throttle/brake master cyl on. Split the housing carefully and note position of wire and throttle cable parts. If memory serves, you remove heater feed wire and partially reassemble to hold the throttle tube. Take very thin screwdriver and slide under the grip at various points to loosen the glue, perhaps spray in some alcohol (some have used WD40). Let soak for a bit, then put blow-off nozzle between grip and throttle tube (do not insert too far if you can avoid it). Blow a little air, and it might just be enough to release the grip, and pull at the same time.
Clean the inside of the grip with alcohol to remove the glue and WD40 (has silicone in it). Switch out the throttle tube with your new G2 and reassemble without grip wire/test. Spray enough hair spray to wet throttle tube and slide grip back on. Alternate, use a small line of high temp RTV gasket maker along the tube (not too much in case you want if off again some other day). Use a little air if necessary. Be sure to position grip in same orientation as before you took it off. Reassemble all the goodies, test that you haven't trapped the heater feed wire, etc.
Perhaps others have had a different method, I'm just relating what I did (from memory).
PS - just noticed you aren't far away...... PM me if you like.