FYI, my diagram of what I did on my '82 westy

http://www.members.shaw.ca/albell/mods/lightcircuit.html

(i did that diagram years ago, I advise going over it carefully to
check for any errors)

ken lewis' description is here:

http://www.vanagon.com/info/articles/upgrades/headlight-relay/index.htm

alistair