OK to install a mod...

Ok if its a mod that u downloaded and inside the folder is something that says mission.lvl Then u have to do this.

1.Go to documents, right click and click new then new folder!

2.Name the folder Backup!

3.Go to LucasArts then GameData then data.

4.Go to LVL_PC go all the way down to the bottom move the mission.lvl to the backup folder

5.Copy the mission.lvl u downloadedto the lvl_pc.
Then u will have ur mod in ur game!