So you are saying you have 9+ for the PRI and want 6+ to be for the analog CO Lines?
You will need to build a new trunk group, and one or more new routes... then add all the possible 6+ dial access codes into Digits Dialed and assign them a route with the CO lines as the trunk group, making sure to pay attention to COR Groups as well. If it was me, I would build mirror routes to the PRI routes, then export the Digits Dialed form, and do find/replace to make all 9+ entries 6+ and just substitute the mirror routes and reimport.
If this sounds too complex for you, I suggest contacting your vendor... ARS (Automatic Route Selection) can be overwhelming, even for trained technicians in some situations. So if you are going to tackle this by yourself, backup, and make changes slowly and test as you go along.