Digital Certificates in corporate environment

I have macros in the VbaProject.OTM which is copied down to each user via a
logon script. I have a Certificate Server on my Domain Controller that has
created a .crt file in the standard CertConfig shared folder. This
certificate shows up in as trusted by all the computers on the domain.

How do I sign the VBA code with this certificate?

I do not get this in my list of certificates to choose from, if I copy the
certificate to my personal certificates I can choose it but Outlook refuses
to save with that certificate attached.

I need to deploy the macros without the need for the end user to go through
the process of installing the certificate on their machine. How is this done
or is this possible?