If you can canabalize a 4 AA or 4 AAA battery holder from some place, you can *carefully* wire it by attaching the ground (black) to the spring in the bottom, and attach the red where the top of the battery (the nipple) sits. Kinda clunky, but it should work to get you through. Make sure the red doesn't contact the switch except when you depress the button (test it with the batteries out of the holder first)
ETA: Necessity is a mother (or something like that)

BTW, that will give you around 4.8 v to start and drop down to around 4v. Don't get spoiled