Thankfully, I've avoided CDG for most of this year. I have never seen a Skyclub there, maybe you mean the AF lounge? I think they will tell you "it is not possible". Unless you are Plat, Diamond or flying in BE they usually only allow one guest. You might be able to talk your friend in if you're only BE if your friend has a Skyteam boarding pass. A Skyclub membership doesn't help internationally. My experience may be a little dated but this is what I remember.