I have a project that I needed to use a keypad and an Arduino Mega to open an electric strike for a door. Anyways I wanted to submit this to see if it was useful to anyone else. If anybody wants to help refine this code, I may have a spare BV4505 to send you. LMK
http://www.byvac.com/bv/bv4505.htm
http://github.com/flyrdm/KeypadBV4505