Clean it really well, wipe it with acetone- not alcohol (this is important). Scuff the bond line with at least a scotch brite pad. Wipe with acetone again. Then use 3M 4200 or 5200. There are differences in cure time and ultimately the adhesion. If you prep well, then I think the 4200 will work well for you. But you have to work fast if it is a warm humid day.
Retail is usually $16-20 for a 10 oz tube. If you look, sometimes you can get it for $13 or so. If you are in a hurry, you can pay $23 for 3oz!. Jamestown distributors had a special a little while ago- and it looks like they are still running it.
http://www.jamestowndistributors.com...hesive+Sealant
That's what I did on my fuel tank hatch. Although I didn't prep as well, as I knew I'd be digging back in there to recore the hatch this year.