The way to do this with a relay is a sequencing relay from a old phone central exchange switch. Since each exchange had thousands of them, they still exist,the last were pulled from service in the early 90s, but they are out there. You'd need a DC supply for the coil, anyways. Their contacts can't handle much current, so each contact needs a booster relay. This is going to need more then two wires, anyway you do it. You really need a memory element relay, which flips like a mousetrap and is manually reset. Since I have no seen any that were not made in World War Two, I think you may have a issue finding those. I'm posting this just to answer your question, as relay trees are expensive to build.
As for latching relays, The cost of the latching relays will exceed the cost of doing this with DMX. AC latching relays sell at well over 90$ new.
I'd go for the DMX board myself. Or have a friend program you a microcontroller...
Keywords: Strowger Switch, Uniselector, Stepping Switch, Step Relay.
The Robber Barons of Nebraska have some, but pricy:
http://www.surplussales.com/Switches/SWLedex-1.html
Steve
Last edited by mixedgas; 07-13-2014 at 09:51.
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