This shell makes it possible to wire out a external supply.
I've tested the fit, but haven't finished the construction.

use a supply like this http://www.pololu.com/catalog/product/2101
wire it out to a wall wort, or a larger battery.
use http://chdk.wikia.com/wiki/CHDK to set up a motion sensitive HD security cam
add a Eye-Fi card for remote network upload.

Put copper strips in for the contacts
when looking at the cut out
Left [+] [R] [-] Right

[R] needs to be connected to [-] with a 10k resistor to simiulate thermistor a normal battery would have. Adjust the power supply to ~4V.

this is one of many articals on this hack.
http://tinkerlog.com/2012/05/13/battery-adapter-for-canon-powershot-sx200/