I once saw a post about using the screws inside your helmet from the ears to hold them in place. Essentially I carefully made a mark where the screws from the ears stick out unto the strip, drill the holes to be very snug, placed it and then mark the holes for the other side, and drill those. The tension is enough to hold it in place.
EDIT:
Found it! I actually ordered my lense from him and it does a great job of keeping your eyes from showing.
http://www.whitearmor.net/forum/index.php?showtopic=14974