Here are some instructions from the TA FAQ:
To manually retreive your password, please go to
http://stats.distributed.net/rc5-64/. In the "Participant Stats" search box, enter the first portion of your email address, and click search. It should return, possibly among others, your specific email address as you entered it in the client software during installation. Click on your email hyperlink on the page. On this new page (your personal stats page, for future reference - you may want to bookmark it), there is a hyperlink at the bottom labelled "I cannot remember my password. Please email (my) password". Click this link and the D.net server should email you your password almost immediately. Note the password and retain the email for your archives.
5) Click on this hyperlink:
http://stats.distributed.net/rc5-64/tmsummary.php3?team=10635. This will take you to the Team AnandTech stats page at D.net (sometimes the page is down temporarily during stats updates, please wait an hour or two and try again). Near the bottom of this page is a hyperlink labelled "I want to join this team". Click it. Your browser will request a user name (your full email address), and a password (from the D.net email). Click OK.
6) It should then take you to your personal stats page, and near the top of this page it should read:
Team: 10635: AnandTech
7) That's it! All packets previously cracked will be credited to Team AnandTech at the next stats update, and all future packets will be directly counted as team submissions.
Basically, you have to wait until you have flushed some blocks to DNet (which I assume has happened), then go request your password, then join TA.