According to the WDL Manual, on page 70 it says that the Multimedia portion of A5 cannot yet be used by dll extensions, but if you could tap into it that way, then it seems like all you would have to do in your wdl script is to tell it not to play like:
play_cd 0,0;
this tells the script not to play any tracks, but it has to be repeated about once a second.
I could be wrong, but that looks like the answer to me.
