In-house Trusted Certificate
Yes, you can create an internal certificate and then a MS Group Policy can be setup whereby each computer in the domain automatically "trusts" any code signed with that certificate.
The Group Policy Item is:
Computer Configuration -> Windows Settings -> Security Settings -> Public Key Policies
In our case, we created an internal CA and put any certs made by that CA as trusted. I.e. it was in the Trusted Root Certification Authority section.