Anthony;

I don't recall my exact response, but it probably went something like: ...first, you must decide the type of switch you want to use (momentary or latching mechanical function), then your electrical options become clearer...and also if you want to eliminate "unwanted reactivation"...BTW...I hope that $42 is for one of the electronic 240 OD relays which eliminate the "unwanted reactivation", because for a simple three or four terminal relay, you should pay no more than $10! ...and these are available all over the place...

See also: http://www.sw-em.com/OD_Retrofitting.htm#Wiring_of_the_OD

Cheers