Several manufactures make line lock kits. I just finished my installation, it was pretty simple.
Hurst makes a nice unit, Hurst p/n#1745000. I would also suggest getting the hurst installation kit (p/n#5671510), and most importantly, purchase the adapter fitting kit for the mustang (Hurst p/n#5671516), the adapter fitting kit makes the instaall simple - without it you'll have one hell of a time trying to find all the proper adapters and fittings. the adapter kit also comes with specific mustang installation instructions.