^^^^ I would not recommend that. The heat could potentially screw up your reso head.
What I would do (It's more work, but you're safe, in other words, your head is 100% safe). Get a CD or something along the lines of the hole you want, place it on the head, and just cut around it with a carpet knife. If you screw up with the cutting, i.e. have an uneven circle, don't worry about it. No one will notice, unless they take a close look... Afterall, it's for the sound, not the look anyway!