PureFTPd and MySQL: error exit status 252

OK, got it working - the answer is here:
http://www.howtoforge.com/forums/showthread.php?t=30115

I had to build the pure-ftpd package using this (from within the source directory after editing 'rules'):
dpkg-buildpackage -uc -b

Then install using:
dpkg -i file.deb (file being whichever of the created .deb files is appropriate for the OS)

I've pinned it so that it doesn't get overwritten when I update.