I just edited the instructions in this thread, they were out-dated...
There is a link to the members map on the portal page menu. When you click on the link, the map should open in a new page, and there should be a pop-up window in the middle of the map to add yourself to the map.
Be sure to put yourself on the map with your forum user-name, so that it matches the forum.
Looksl like the map host site is down... The map is hosted on the Platial.com site. I would like to figure out how to host the map myself to keep this from happening- I'll put it on the project "list".