Check this out... it's the best guide:
Rolex bezel tutorial
The removal is careful prying with a knife between the lugs and the bezel itself. You have to take care not to lose the tiny spring, nor damage a thin stainless ring. The first time I did it, I got beneath the flat metal ring and bent it slightly. Took care to straighten it, and more care each time I have done it since then.
The bezel insert snaps in and out. From what I have read, the tolerances are very close, and one of the reasons to make sure you use the original Rolex part. In my search for the Pepsi, I saw several that took glue or otherwise and wasn't too keen on those methods.
After alignment, which isn't difficult, you press the new insert in place around the bezel. The tutorial shows pressing against the table, and that is precisely what it took to get that last bit to snap in place.
The bezel, with insert, is then snapped back in place.
I was probably more ginger and gentle, but didn't damage anything and it works fine. The bezel on the Sub works the same way. The primary difference is the small spring, which only permits unidirectional travel of the bezel. The GMT is rounded on the end so it will turn both directions, but still offer the detent.