I'd be guessing just as much as you on a job like this. If you can't get it I can play around with my car since it has the same instructions for removing the cylinder as the 9G. Although the 9G strangely you can steal the entire glovebox it seems whether its locked or not....8G you have to open the glovebox to be able to remove it.
The second part of the equation is how you would get the replacement cylinder keyed properly...that part I don't know. At that point it might be a good idea to take it to the dealer and be like "yo how do I replace this cylinder".
EDIT: Also....it's possible the cylinder isn't the problem but there's something messed up with the latching / releasing mechasim. I don't know how to diagnose that...in my mind once you remove the cylinder you should be able to use a screwdriver or something to release the latch manually.
EDIT EDIT: If you're dealing with Tempe Honda...I don't think they're going to try to screw you. I've used them a few times and they gave me good service.
Can you take a pic of what it looks like with the cylinder removed? Does the cylinder turn with the key now that it's out of the latch? When I peeked a flashlight around my lock, it looked like moving the key cause a piece of metal to move left and right...probably a disconnector or something for the handle. The lock cylinder is just a keyed turntable so I imagine a flathead screwdriver or maybe 2 opposing flatheads will be able to do the same thing the cylinder does.
OK I figured it out. Was able to remove my lock and pop the glovebox.
You need to get a metal stick of some sort (i have a metal hook/pick set that has a straight pick) and stick it in the red circle and then pry that to the right. Took very little force. Glovebox opened right up.
This is the bottom of the cylinder (the side with the notch)
EDIT: Got my orientation wrong. The side that says SDA/4 is the left side of the cylinder. In the pic the lock is ... locked .... because the key is in line with the text.
And for future internet people: here's how to remove the retaining ring thing. Right angle pick under the black wire with a lifting (twisting) motion:
Reinstalling the cylinder was "shove it in, lift and push the retaining ring back where it was". I didn't have to remove the glovebox...so the service manual is probably being excessive in recommending that (not surprised).