I have this same issue on one of my Z3s as well. I routed it to smart key using 005b seem map. Here are a couple options for you depending on what key you would like to make the camera.
seem 005b - offset 18. Value is 15, change to 3F. (changes to smart key)
seem 005b - offset 1C. Value is 2B, change to 3F. (changes to voice key)
seem 005b - offset 1E. Value is 42, change to 3F. (changes to browser key)