This is a howto for installing a mitsubishi spoiler on a 01-02 Sebring/Stratus Coupe. A pretty simple affair, but a bit nerve racking drilling through the trunk lid.
The 03+ are probably very similar but I can't confirm it.
The spoiler I have needs to be attached via 4 bolts. That means positioning the spoiler on the car where you want it and marking the drill locations.