@dbemowsk
Just an idea, use a dimmer in domoticz for the volume, when you receive a value from the controller, then send VOLM and the value.. There is no need for the controller to know how to set the volume (the VOLM command)
For IR commands, that's probably another story, Haven't looked that much into it (yet).. Right now I have a logitech harmony elite, integrated with domoticz, so that I (from domoticz) can turn on different scenes.. But I can not send an individual command to the tv, or the radio..