A warm welcome from me
I've had an instrument cluster on the test bench. It can be communicated with just the CAN gateway from the OBD port for diagnostic work but it's not lit up.
If you want the cluster to be fully working, lit up, dials moving etc.. You need the Entry and start authorisation control unit, working keys, steering column, etc, etc.. Ideally all from the same car otherwise component protection will kick in and there will be limited function from the cluster. I've haven't done that as having a working cluster wasn't my goal.
I've tested at few control modules on the test bench, analysed the CAN networks, and flashed new software to them. Occasional bricking modules in the process!
Current flow can be found here, document 2
http://forum.a8parts.co.uk/showthread.php?t=9347