I found on the cPanel forum that DomainKeys was already installed in the version of cPanel I have on my server.

Apparently, with my setup, all I needed to do was to install it and make sure that the DNS was set up correctly. This was done by logging into my server and typing:

/usr/local/cpanel/bin/domain_keys_installer <user name>

Where <User name> was the name of the user for the zone that I wanted DomainKeys set up for.

The installer made an entry in the DNS for the particular zone.

I use an external DNS service and so I had to copy the entry that was made automatically to my DNS service.

This was  the default._domainkey entry… So in my eternal DNS service I created a TXT entry named default._domainkey and copied and pasted the value that the installer had created.

I also created another entry:

_domainkey “t=y; o=-”

The only thing left to do was test the setup. I sent an e-mail from my server to a Yahoo account and Yahoo deemed that I had an acceptable DomainKey.

I also sent an e-mail to: check-auth@verifier.port25.com

which also replied with positive results.

I found that a lot of tester out there gave negative results, but I am assuming that the testers were not up to date with the latest DomainKeys standard.