WMP playlists burnt on data disc, playing FLACs on the data disc?

I'm not sure how to do this.

So when the disc is in, I can quickly open the playlists on the disc that will play the flacs from the disc.

Before you try to play FLACs on WMP I would first ask if you've installed a plugin that'll make it possible? WMP can't normally play FLACs. I've never done it so I can't recommend one but there are supposed to be several free ones available online. Also, the playlist has to be in a format WMP can recognize. If it's not, create a new playlist form the files on your disk in WMP and burn it to your disk. Once those prerequisites are in place, if you still need help we can discuss opening the playlist and playing the files.