I haven't actually used mine to bid on anything 
since I ask either of the Celgas to do that, but 
I got a yahoo jp ID just to navigate through 
auctions more easily.

Although this site is a guide for stock quotes 
via Yahoo JP, it still applies here (for the most 
part).

http://www.gaijininvestor.com/portfolio.htm

The only thing you need to lie about is the 
postal code, and you can just use the one in the 
example.

You can pretty much figure out the rest of it by 
using a text translation site like this one:

http://www.elingo.com/text/text.php3

Just cut and paste the Japanese text in there and 
simply let the site translate.  Later.