On Sat, 25 Aug 2012 16:09:39 -0700 (PDT), Richard Russell wrote:

Insteresting but that only works with 2 switches. The OP has 3, hence
"3 way"... *B-)

It can easily be extended to 3 (or more) switches:

http://www.rtr.myzen.co.uk/neon.gif

As shown that lamp should be on. B-) IM switch in "swap" rather than
"across" connection mode.

It was late last night and I was tired. B-)

Doesn't work if you connect the load to the RH switches L1 or L2 which is
what I had last night by simply inserting an IM switch between the change
overs.

With three switches the load has to be on the other side of the "supply"
change over switch. With four or more switches the load can be any where
except on the last change over switch. I think...

--
Cheers
Dave.