This page describes stuff that needs to be done if you're elected onto the PMC (see ProjectRoles). It assumes you've already been a committer and performed the tasks described in BecomingCommitter.
This should wait until the board has ACKed the PMC addition and 72 hours has passed without objections.
Grant the person's Bugzilla account with all permissions, and with permission to grant all permissions to other users. This is done by following the "Users" link in Bugzilla, specifying the account by email address, clicking on the correct username, scrolling to "Group Access" and ticking the appropriate checkboxes.
The private at spamassassin.apache.org mailing list is used for PMCish chat (see ProjectRoles); your Apache email address is added to this list.
http://www.apache.org/dev/pmc.html#newpmc notes: 'your PMC chair needs to update https://svn.apache.org/repos/private/committers/board/committee-info.txt to denote the new PMC member's details and the effective join date.'