I think that P3P standard is 'dead'. See these posts:
http://www.cylab.cmu.edu/research/techreports/2010/tr_cylab10014.html
http://www.zdnet.com/blog/facebook/facebook-to-microsoft-p3p-is-outdated-what-else-ya-got/9332
http://www.techpolicy.com/Cranor_InternetExplorerPrivacyProtectionsBeingCircumvented-by-Google.aspx
You don't need anymore a P3P editor. Just insert an header like:
CP="This is not a privacy policy!"
This is an invalid P3P policy but internet explorer with an invalid P3P policy simply consider your cookie good and it isn't blocked.