You will need an EXTRACTED version of left4dead e.g. Skullptura version.
EXTRACTED, NOT IN .GCF files.
Read NFO for instructions.
What will this fix do:
# If you have a real version, this patch won't work (not extracted), unless
you manually extract game files.
# If you have an extracted version that needs Steam to player over LAN/Hamachi,
This fix will get rid of the Steam part so you can uninstall Steam, and still
keep LAN/Hamachi functionality.
# If you have an extracted version that does not need Steam but cannot play
over LAN/Hamachi, you will keep the deSteam and now be able to play over