"I got him long ago. I think I paid $1.99"

Yes, had them for a long time, too, but he pretty much collected dust until I re-rigged him. I think he was even free a few years ago, shortly before all 3rd gen stuff got vaulted.

 

"But how do you weight map him?"

That's not easily answered. The process itself is pretty straightforward:

You open the joint editor and convert the conventional rigging into weightmaps.

Then you edit the weightmaps with the brush-tool to refine the joints.

But it's like sculpting a morph: You can tell somebody what the tools do but you can't really teach how to find the correct shape. You have to find out for yourself just by doing it.

But there are a couple of tutorial videos online that might be helpful:

http://www.youtube.com/results?search_query=poser+weight+mapping