Custom action on keypad device?

Maybe I am missing something, but I'm not able to create a custom action to execute commands on a keypad device. I'd like to be able to set armedHome, etc, based on triggers from other devices.

My use case is that I'm trying to use the keypad as a general-purpose 'button' to execute other things. For example, I want to set it to armedHome when the garage door contact sensor closes (rule #1 with custom action that calls command on the keypad driver). Then, I want to open the garage door when it is disarmed (rule #2). Any suggestions on how to get this done?

FYI @bravenel

You can select the keypad using one of its capabilities, for instance, Motion.

Thanks for the quick reply! That was the piece I was missing.