Do you want to use the CME MoH that you have configured? If so you should be able to use the Hold and Unhold steps within the Call Contact pallette.
Are you trying to play different music to diffierent contacts? If that is the case you will need to use a Play Prompt or other step within the script. A more common one would be Get Digit String with the music prompt which would allow a caller to press a DTMF digit at any time if they wanted to break the music and go to voice mail for example.
