FWIW, I'm not sure the OBC has a means for directly controlling output voltage. I believe that its fundamentally a current source. The LBC monitors the battery parameters (SOC, temps, etc) and reports to VCM, which tells the OBC how much power/current to output. I'm not aware of any way for the VCM to tell the OBC to output a particular regulated voltage. As a current source, the output voltage is whatever it has to be to maintain the required current output. That may or may not be an issue depending on what you are trying to do.
You might be interested in the thread/videos I've done on operating a 2012 Leaf system outside the car. I've been trying to document the minimum set of controllers required to get the system to startup and operate as normal. Its not quite the same of course, as I'm trying to get drive mode not just charge, but might be of some help.
http://www.diyelectriccar.com/forums/sh ... 51458.html
Post #60 is where I started assembling the system:
http://www.diyelectriccar.com/forums/sh ... stcount=60
Leaving out the brake and steering ECUs should be fine. I suspect the inverter is going to be an issue though. In order to successfully get to ready and begin charging, there is a very strict sequence of events that must occur. Otherwise an HV system fault will be suspected and the battery will remain disconnected as a safety precaution. One of those key gates is the inverter telling the VCM that pre-charge is complete (based on voltage sensed at the inverter caps) and to go ahead with closing SMR1 to complete HV activation. Similarly the HV has to be detected in the proper sequence through the DCJB (PDM in the 2013+ I suppose) to allow the charge relays to close and charging to begin.
From the codes you listed, I'd start by looking at your 12V power system. P3196 could be a CAN problem, but also could just be the OBC controller is not powered correctly and not responding. B2098 also seems to indicate an issue with your ignition on 12V power sequencing as detected by the IPDM. P189A is probably a consequence of not having the motor hooked up, so it can't verify its in park. That could also be an issue.
One more thing you could try, a friend has told me that there was a guy over on the focus electric forum who succeeded in using several Leaf OBCs as add on chargers for his Focus. He's pretty sure its this guy, who has moved on to a new approach and seems to have deleted the earlier thread. You might try contacting him...
http://www.myfocuselectric.com/forum/vi ... =16&t=2548