I have once or twice taken these flights booked as LX flights, probably booked last minute.
The lounge situation is horribly complex which is why I hesitated replying, not being sure any more and these things are in any case liable to change.
I believe you may (and the may is because it depends on who you encounter guarding the lounge) have access if you have an LX ticket and obviously the right to enter the lounge. However, things get complicated if you have a low-end economy ticket and FTL card. Your chances of getting into the lounge (which are pretty miserable anyway) go down.
If you have an AF ticket, you have no chance (unless you're in business or have a suitable AF/KL card).