[mikethedruid]

OK, my own two cents worth... I agree this is such a small and precise area that spray adhesive, while fine on the grill cloth side, may not be ideal for this application. (pun intended) You are looking to merely hold the gasket in position until the speaker can be secured after it. For this I would mix up a small batch of 5 minute 2 part epoxy cement, and spread it thinly over the edge where the gasket will lie, then position the gasket. It will remain soft long enough so you can reposition the gasket if you don't get it quite right immediately. With contact cement that is not such an option. (Been there, done that in slightly different circumstances) That's why I would use 2 part epoxy for this.