Back again with an update. Was unable to find a service manual for the lacrosse :/ but as it turns out the inverter module is the same for the 2013 Chevy Malibu, which is quite a bit more common. I purchased a manual and lo, there are some rough one line diagrams for beginning the reverse engineering! Anyone have any idea where I could find a list of GM CAN declarations (request torque / whatever).
Electric Motors and Controllers