Instructions
Open Windows Explorer on the computer that is hosting the "Garry's Mod" server and locate the HLDSupdatetool.exe file. This is the file that you normally use to update your server. While most server administrators place that file in the main "Garry's Mod" server directory, you might have chosen to save it elsewhere on your hard drive.
Right-click on the HLDSupdatetool.exe file and select "Properties."
Enter the following code in the "Target" field:
Replace "gamename" with the code of the game whose content you want to import into "Garry's Mod."
If you want to import "Counter-Strike: Source," type: "Counter-Strike Source"
For "Team Fortress 2," enter: "tf"
If you prefer to install "Half-Life 2: Deathmatch," type: "hl2mp"
Additional codes can be found at GarrysMod.com.
Click "OK" and double-click on the HLDSupdatetool.exe file to start the update process.
hldsupdatetool -command update -game "gamename" -dir