Changing Contact Code Default when making contacts in CRM and pushing to Sage 100

When I create a new company in CRM and then add contacts to that account - all through CRM - when I push that info over to Sage 100 it defaults the contact code for the contact to be the Last Name. When we set up our contacts through Sage 100 we use a number system for the contact code (00,01,02 etc.)

Is there is anyway to modify CRM so that when a contact comes over into Sage 100 it defaults to this numbering system instead of a name? I am being told that the integration is on the S100 side so the modification, if it can happen, would have to be handled through Sage.