I just bought a module for my e46 vert... i originally was saving up for a SmartTOP but thats about 300+, i did some youtube/google search and came across this:
i bought the open/close module for 90 dollars shipped (came in 5 days from italy). Other modules and features are available too.
the website itself is a tad weird/sketchy so i just contact him via email and he sent me a paypal invoice. His name is Fabio.
Didnt know about coding, would have went that route, seems cheaper.