"Boeshield T-9" also works, and you can use the leftovers for chain lubrication. It's a wax-containing product. Similar to JP Weigle's and perhaps others.
Spray cans have a long, thin straw dispenser which can often be poked into vent holes in the frame. Or, spray into larger, more open end of chain stays, and then wiggle the frame around (to spread coating), and end up with dropouts at bottom, wait and see if any of the excess trickles out, so that you think you've coated the interior.