This has been something that has been wracking my brain for quite sometime because I want to use my own playlists that I have on Winamp for my own radio station but have absolutely no idea how. I'm using the latest version of the Centova Cast client which is 3.2.5.

Is this possible?

If your host is willing to enable M3U playlist support, you will be able to save your Winamp playlists in M3U format and use them in Centova Cast, by following this procedure:
http://www.centova.com/en/faq/cast3/information/can_i_create_an_m3u_playlist_and_upload_it_to_centova_cast