Homelink-Style Remote Cloner

Hi, folks. I want to put a control system on my garage door opener that pays attention to some household parameters and actuates it up and down. I'd like to do it like Homelink where the control system "clones" the remote and rolling code setup and actuates it through RF. Other than going through Microchip and Keeloq encryption / decryption, what is the state of the art in doing that now?

Any suggestions?