When looking in my outbox, there is 2 messages that you missed on 2009/03/26. One of them contain a procedure you were supposed to do with Koitsu. Since you never read that, I saw that as a possible lack of interest about the wiki admin and didn't force it by mailing again.
Those 2 messages don't contains the credentials: once you do the procedure that Koitsu asked, I or Koitsu will send you back the credentials.
Once you get them, only do admin task with the main account. As for the rule, we can talk about it by PM but I don't think is something secret or anythings
Edit:
If credentials were sent (if any), it must have been around that date. I didn't keep them in my mailbox for security reason so I cannot confirm.