Hi, very noob, but have read allot over time, but half of it Ive forgotten, and well... here I am :-P

I intend to replace some buttons with in car android custom software running off rasberry pi 2.

Can I somehow using an OBD II (ELM 327) connector, listen to commands being dispatched through the car? It seems it will be really difficult to figure out these codes/commands, do I have to build a specific device? or can I do it through elm327? Or do I need canbus? I'd like some direction on this if possible.

Thank you