Standalone AC/DC Charger and 3AAA Battery Combo

[tylude]

My goal is to build a stand alone charger with an ac/dc coaxial connection as well as the option for charging with 3 AAA batteries. My zip zap is running the dual batt mod and I want to create a good charger for it. I am summoning the zip zap guru's out there for a solution. I went to rat shack and got a coaxial adapter, a 3AAA battery holder and a medium size project case. I am using the base off a dead zip zap controller as the charging point. My goal is to hook it up so that it is switchable between the battery and the adapter automatically like the controller mod in the zipz zap faq. What points on the coaxial do all these things get hooked up to? For instance the shell is the negative from the controller but since there is no controller then what gets connected here to make it switch between battery power and ac power? Any help out there would be appreciated.