Please follow this steps to use mission packs or mods from the command line:
1
Quit Quake II.
2
Copy the folder of the mission pack to your "Quake II" folder. The "Quake II" folder is the folder that holds the "baseq2" folder.
3
Open the application "Terminal" which is part of the MacOS X installation.
4
Change to the directory that holds the Quake II application. For example: "cd /Applications/Games/".
5
Start the Quake II application by appending the command line parameter "+set game" followed by the name of your mission pack. For example: "./Quake.app/Contents/MacOS/Quake +set game game ROGUE".