Sorry i dont think Half-life is compatible with 6600 or Ngage. The application closes as soon as you open the first door. HOwever it should work on the newer phones.

1- copying the "wad" file to your memory card E:/ .
2- I renamed the file to "doom2.wad"
3- Open c2Doom
4- Press Menu >> Advanced >> Reset WAD file
5- It will ask "Use This WAD file? E:\Doom2.wad"
6- Press Yes

NOTE: To play the normal DOOM version it is DOOM1.WAD. DOOM 3.WAD is the multiplayer version. So if you try to load it and choose single player you will get an error:
"Error: W_InitFiles: no files found"

If you still get an error try posting the error with what you have done exactly.

And thnx for the sticky