You can start mission packs with AppleScript.
Open the ScriptEditor located at the "AppleScript" folder inside your "Applications" folder.
Create a new script with the following three lines:
tell application "TenebraeQuake"
run params "-hipnotic"
end tell
Replace "-hipnotic" with "-rogue" if you want to use Mission Pack 2.
Save the new AppleScript as "Application".
Open the ScriptEditor located at the "AppleScript" folder inside your "Applications" folder.
Create a new script with the following three lines:
tell application "TenebraeQuake"
run params "-game MOD_NAME"
end tell
Replace "MOD_NAME" with the name of the mod.
Save the new AppleScript as "Application".