2. Download the Source SDK Base under Tools in Steam.
3. Then download the .zip or .exe version of GoldenEye: Source here.
4. Install or unzip gesource to your Steam directory, under "SteamApps" and then "SourceMods"
Usually:
C:\Program Files\Valve\Steam\SteamApps\SourceMods
Or:
C:\Program Files\Steam\SteamApps\SourceMods
5. Restart Steam when the installation is complete (make sure you completely close the program and not just minimize it onto the taskbar!) and Goldeneye Source should appear under your games menu.