Hey,
Don't know anything about getting the Throttle Meister off, but once it & the other regular bar weight is off then get a small blade common screwdriver & some WD40 (or even some Windex if you don't have WD40).
Work the screwdriver between the grip & the bar squirting the stuff liberally & work the screwdriver all the way around the bar till it moves around the bar & all the way up to the far end of the grip & then just slip it off.
Clean off the bar & squirt some Windex on the bar & in the new grip & work it on the bar. It needs to sit for a few hrs. to dry out before you start torqueing it around.
Pretty simple really. Some guys use compressed air - I have a large air compressor & it's piped into my garage, but this easily worked for me w.o. needing compressed air. :Flash: