Absolutely this can be done and has been done many times before. On the CCM side, you will need a route pattern to send the call to an Inter-cluster trunk or as an H323 Gateway(CME's IP address). From the perspective of the CME router, create a voip dial-peer that will send patterns that the CCM 6.x will have. Will work just fine.
As a note, you will want to use g711 between the integration, as CUE is G711 only.