You can buy the spring-lidded caps from Powerlet Products
(PSO-001 $2.95), and the connectors from Parts Express
I used the round DIN female connector (surface mount, front mount, with locking nut) mounted through the cap base and stingray with the nut behind it all, and a cord-end matching male connector. I just soldered about eighteen inches of wire in a straight-through configuration between the connectors.
So the female jack and the cap are on the stingray, the 18" wire runs back towards the area under the rider seat, and the Autocom rider lead plugs into this connector under the rider seat instead of hanging out over the side.
Basically, all I really did was make an extension cord that had one end mounted on the stingray. I did it this way so that if there was a failure in my wiring, all I had to do was lift the rider seat, unplug the extension, and use the factory Autocom lead as if my mod was not there.
Same concept for the topcase/pax connection. The plate with the power plug is, as Grif pointed out, held on with two allen screws. I mounted the same type of extension there and fed the other end of the cable out through a grommet. The Autocom pax lead plugs into this pigtail and I stuff it down in the recess between the pax seat and the topcase. This allows me to unplug iit easily (without removing rear seat) if I take the topcase off of if a problem with my wiring develops.
So far, it works like a dream!