SpamAssassin SA-Update for additional rule channels
Modify the SA-Update script to allow configuration of additional rule channels to be incorporated with the usual single daily execution of SA-Update. cPanel could implement this using WHM to allow specifying as a configuration item the --channelfile parameter so rule channels such as sought.rules.yerp.org could be added to the default updates.spamassassin.org rule update channel. You would also need to add the --gpgkeyfile parameter.
You could also leave the default updates.spamassassin.org --channel and its --gpgkey hard coded into the SA-Update script and just allow users to provide other optional rule channels to be implemented via --channelfile and --gpgkeyfile.