I install my sound hole grommets after I poly everything, I use superglue to place them in the hole and after they're secured I put another bead around the inside then seal the whole deal with some hot glue. I poly the box first then if you have any of the super glue spill out on the box you can hit it quick with a towel and wipe away the excess.
To glue the grommets to the box initially I put a small bead around the rim on the part that will make contact with the box and put em' in place. You have a couple seconds to move them where you want them then wipe away any residue. Seems to work well for me and I have never had one move, as a matter of fact I tried to take one out once because I wasn't happy with the look and tore the box apart trying to remove it. They hold well!
P.S. More like "Jack of all trades, Master of none" for me Mark :-)
It was great to meet another boxhead like myself, glad you made it home safe and sound! It was a crazy weekend for us at JunkStock, sales were better than we could of imagined. Fantastic show and great people like yourself make it so much fun, it was fun talking with you and I'm sure we'll be seeing each other again :-)
Couldn't wait to get started on the next build huh? You've been bitten by the CBG bug I'm thinking.
Thank You so much for you're kind comments, I am always flattered when people like what I do. You do great work yourself! Look forward to seeing some of your builds.