A LEGO double-throw switch?

   So I've got an application where a forklift loads a crate onto a conveyor
belt. I could then start the conveyor belt up by having the forklift throw a
polarity switch. What I would *like* is that when the crate gets to the other
end, it somehow stops the conveyor motor again, (here's the tricky part),
leaving the system in a state where the next forklift delivery can re-trigger
the whole system from the "front end", as it were.
   Oh, did I mention I wanted to do this with just polarity switches, no RCX or
other "intelligent" systems in the loop?
   The picture I've got in my mind is something like a light with two wall
switches - change the state of either switch, it changes the state of the light.
I'm thinking I can do it with a looong string from the terminal end back to a
polarity switch at the head of the line, but it seems... clunky. Is there any
electrical solution? Can I reproduce my household wiring in LEGO (I promise I'll
keep the voltage... a *little* lower)?

-- 
Brian Davis