How to get Wiki edit access
Go to the forum User Control Panel. The link is in the header, next to the logout link.
From the control panel go to the Usergroups options (three links below Profile)
In the far right column, select the radio button for WikiUser. Make sure the drop-down box next to the submit button reads "Join selected" and click Submit.
Congratulations, you can now edit the wiki! Your login credentials for the wiki will be the same as the forum although you still have to log into it separately.
If you want your wiki edits to be attributed to something other than your forum username, edit your forum profile and put something in the new Wiki Handle field (it's just below the birthday settings).
Note: This is the current process for getting access. As things change, this topic will be updated. Post questions on getting access below.