It looks pretty simple to get the combo if you have the serial number. It will cost you $12 and a notarization.
http://www.firefyter.com/pdf/combo_request.pdf
You can't 'manipulate' a electronic combo safe (ala Matt Blaze, that is for mechanical safe locks only). They sometimes can be bypassed, but not always. Of course, a little fire proof safe won't stand up to Mr. Bosch too long either.

However, I would just save myself the trouble (and potential/sure damage to the safe) and spend the $12 unless this is purely a challenge project.