I've seen the one that has a large rectangle you need to install, it also needed you to hold the button as it pulled the e-brake and with that I though it was too large, heavy, and impractical...
http://www.estopp.com/#!about/c1x9v
I would like to see a line-loc version you found, sounds much more practical and I'd love to eliminate the e-brake handle/pedal for a cleaner look! It would only be a parking brake instead of an e-brake but I'm ok with that!