I bought two "switched" powersupplies each 6V DC at max 4 Amp. and made a small adapter that fits in the battery compartment.
To limit the inrush current (after switch on or flash) you need 1 ohm limiter resistor in series (or like I used 2 x 0.47 ohm).
See the photos:
DIY power supply on Flickr.
The photos on Flickr have some "notes" that further clarify some points.