liblist.gam is the file for Half-Life 1 that specifies which gamedll to load. It can be found in every mod directory (cstrike, tfc, dod, etc); although with Steam, it may be located inside the content cache files.
This is a key point in getting MetaMod to load. You must modify either the gamedll or gamedll_linux setting (depending on which OS you are using) to point to the location of your MetaMod .dll or .so.
- gamedll "addons\metamod\dlls\metamod.dll"
- gamedll_linux "addons/metamod/dlls/metamod_i386.so"