Sorry, but if you are a dealer, I can`t understand why you are doing such an installation... Your customer has a BV7 MKIII with a fantstic and easy to use Cinema feature. So, why not use that? Just get a Lintronic -238 box, connect it to the cinema out and let the box control all devices by executing a macro triggered by the digital inputs. Should work easier and much more reliable tha your installation. In your setup you have three (?) IR points, BV7, projector, screen. What happens, if you press "Cinema", the BV7 will get the command, the screen too, but the Projector don`t?
Your customer will have great surround sound, a 100" white screen and no picture at all. If you now press Cinema again, the projector will eventually turn on, but BV7 will turn back to TV mode and the screen will come up - useless.
But to answer your question, yes, you can program a macro that starts with Cinema function (FORMAT - 0), and afterwards send the 3rd party commands.
Stefan