A new version of Policyd is out, it runs as a Perl module and not as a daemon, I've begun looking at upgrading to this version. More modules will have to be installed first, though, to support this, including configuring amavisd-new, which I'm not currently running.
I think I've also found a workable install process for imagemagick, my past attempts at getting this going have all failed. The steps I've found include a number of additional modules which appear to be either required or strongly recommended, and these may not have been installed previously. My last attempt at doing this via MacPorts failed miserably, including having two separate version of Perl installed, which I think I've now managed to remove all traces of.