ShellExecute is capable of doing this, and although I don't script in Plus, I'm sure you can call the DLL and use it as a procedure. ShellExecute might be a Delphi procedure, I'm not entirely sure.
ShellExecute is a function that opens a file to it's default program. So using ShellExecute on a .mp3 file will open that .mp3 file in the assigned media player (Windows Media Player for example).