Millsey,
I too was looking to do this. I did find a msi was created in a previous version of the CRM.
Located here:
C:\Users\username\AppData\Roaming\3CX Ltd\3CX CRM Integration 12.0.474.907\install\3CXCRM.x64.msi
The latest version of CRM did not seem to include a MSI. 3CX could you provide an MSI for the all version going forward?
-BS