I just released a new greasemonkey script to archive all personal messages on IPB based forum, implemented for softpedia forum.
See all my scripts: http://www.ciuly.com/greasemonkey/
Direct download link (non-IE): http://www.ciuly.com/greasemonkey/sp_archive_pm.user.js
Do note that you also need the aa_all_common and aa_sp_common user scripts
