Setting up existing Cradlepoint as cellular failover on Comcast Business router

Who do I speak with to get assistance setting up an existing cradlepoint with 4G/5G as a failover? I know in the past comcast could handle this with the existing equipment/router by connecting the cradlepoint to one of the ports on the router and setting it up on their end as a failover. I have had an existing ticket open with Tier 3 Advanced Engineering for a week or so now but no updates if it is possible yet. I am on a bit of a time constraint to get this up and running before the next election so I need to make a decision soon If I am going to try and have our Firewall handle the failover. I am told setting it up through the isp equipment is best practice.