I have a column devoted to RC switches in the May/June 2006 Ships in Scale, www.seaways.com

There are a number of ways to switch something using one channel of your radio.
One way is to rig a servo to push a switch, or even to have your rudder's tiller push the switch... I don't like that because latching switches take a lot of push effort, and momentary switches require that the servo stay rotated to the ON position.

Better is an e-switch like the SES-3 at http://www.mikessubworks.com/switches.html
Plug it into a slot in your receiver... push stick one way to switch one item, other way to switch a second item. Either switch can be set to momentary or latching mode.

Much fancier switching is available too- up to 8, 16, even 32 items.

Pat M