This can be trusted, it was disussed 2 years ago: http://talk.maemo.org/showthread.php?t=47831 but I'm not sure if it will work with current PR (or CSSU) as this stuff was designed when PR 1.0-1.2 was in use afaik, but you can check if you feel brave (unless someone else corrects me that it still works with PR 1.3.1, cssu-stable and cssu-testing)