Linux: copying windows installation / *.vpk files fails to validate

[jungeskemuese]

hi! - for most valvelinux games copying over from Windows seemed to work.
L4D2 makes an exception, though the file/directory layout appears to be identical, ignoring .dll/.exe's.
I'm specificaly not talking about the Beta-channel.
Copying the whole directoy fails to work, as does copying only the .vpk files in the appropriate places initiated by the download (either common/ or downloading/550). Steamforlinux validates 1 file only and continues to crunch away at its 8gb download.

I think I read up on most on it on the net, anybody having further pointers or authorative judgements on cutting corners, I'm happy to hear! :)

Either way, steamforlinux is very welcome.