Hello diegogutierrez,
Have you verified that your source program is compatible with Icecast protocol?, if so, it wouldn't need a user only the main source password.
If however, your source is not compatible with Icecast protocol, then you can still use it by setting up a station with Liquidsoap as the autoDJ handler in Centova Cast. That will allow you to create DJ accounts that use the Shoutcast v1 protocol, even though the main server is Icecast.
HTH