http://eswc.gamecom.plantronics.com/
ENSURE you register an account using the 'REGISTER' button at the TOP RIGHT of the page to avoid Recaptcha problems!
Log in and click 'Home' on the top left
On the RIGHT HAND SIDE of the website under 'Schedule' you should see CS:GO, click 'Register Now' next to CS:GO and create or join an existing team.
Once 5 people are in a team you will receive beta keys in an email! 7 players max for a team.
http://steamidfinder.com/ to find your STEAM ID
edit: Registration has re-opened, unsure if they have restricted it to North Americans only.
Clicking 'Register Now' button gives an Error page
): Just bought a key for $12 three days ago. Hopefully after this there will be a few more aussie servers.
By the way, to find STEAM ID go here: http://steamidfinder.com/