Here you can find the information how to setup the Main Meter in cubase for the probox. As the MCU doesn't support that I have build in a 4th Midiport for generic controller options. The stereo Meter bridge is one of that (beside the other unused buttons that can be accessed via that generic controller)
- add a generic controller in cubase - set the MCU ports 0 to the controller - import the xml file that you want - press ok
there are two xml files in. One is for Meterbridge L-R (its the same for both channels as cubas only sends ONE level) its not possible to send L and R seperate.
the second file (with CPU in the filename) sets the left Master Meter for the output level, the right one for the used CPU power (maybe usefull)
HINT: it seems so that cubase saves only the track numbers. You have to select STEREO OUT. As this is always the last channel the channelnumber can varify on every project. Maybe there is a possibility to set this permanent to a specific value.