They mount the charge plug to a charge receptacle. Yes, it's a commercial gadget. They generally mount to the fuse side with a pair of screws. Before these were made available, many people just let the charge jack hang in the breeze with the wire hanging between the fuse and wing.
Dubro makes a switch and charge receptacle combo.
http://horizon.hobbyshopnow.com/prod...sp?prod=DUB207
Here is the Ernst unit. The specific one shown is for Futaba, but they also make them for Airtronics, JR, Hitec, etc.
http://horizon.hobbyshopnow.com/prod...sp?prod=ERN124
Check out your LHS and I'm sure they will have a couple in stock.
John