Has anyone successfully done this? I can't get it to accept a non-Japanese address as it still expects me to select a prefecture and have a valid Japanese post code even after selecting a different country.

http://info.jees-jlpt.jp/acquisition/myjlpt-id.html

That's because that's the page for the JLPT in Japan (and possibly some other countries, I'm not sure.)

If you're in America, watch this page. Registration isn't open yet.
http://www.jflalc.org/jlpt.html
If you're in another country, you'll have to search the web and find out who administers the test.

I thought that might be the case, the country selection bit just threw me off. I found the application on the SOAS website so I'll take it from there.

Cheers.