How to give button focus

I have a button that, when pressed pulls up a handy form that has lots of info about a user’s mail file and their quota. Included in this form is a button to request that their quota be disabled for 24 hours (so they can clean up). However, I don’t want THAT button to have the focus when the form is pulled up, I want the Cancel button to have focus.

Reason: That form pops up with the info and users are just pressing ENTER, which then sends off a request to have their quota removed when they are intending to simply press CANCEL. (Yes, the could just press ESC but that’s an education road I can’t begin to go down).

Any thoughts on how to get focus over to the CANCEL button?