Does anyone know if Cisco supports using VG248 to connect analog agent phones with CAD on an IPCCX environment? Trying to find the doc that says it's either supported or not.
That's a no-go. You would need to use a third-party product such as Radianta's Remote Agent Express to get off-net or analog agents.
For the record I have not worked with Radianta software first-hand so I cannot attest to how well (of if) it works.