I do not believe I did do that. How exactly would I go about performing said task?
Right well first you need to know the path where steam is installed on your system (usually c:/program files/steam/ ), using the text editor you used top copy our chunk into your GameConfig.txt replace all the occurrences of $SteamDir in your edited GameConfig.txt with that path (notepad has a replace function in the edit menu, which will make short work of this).
Secondly inside your steam folder is another folder called SteamApps inside that is another folder with your steam user name, you need to replace all the instances of $SteamUserDir with the path to that folder. For example :
"Light" "$steamUserDir\sourcesdk\bin\ep1\bin\vrad.exe"
becomes
"Light" "C:\Program Files\Steam\SteamApps\Battle Brother Arius\sourcesdk\bin\ep1\bin\vrad.exe"
Finally re-save your GameConfig.txt and restart the Source SDK. That should sort you out.