i am looking to do the same. the link you showed is how to setup real robot with plc. twincat is easy cause it can be install on a PC or an extarnal iPC. im still lokking for roboguide part. i have sent an email to my ex co-worker at fanuc to help me out.
I have talked with Beckhoff and they said the computer needs to have (minimum) two ethernet adapter and they should be connected to each other by cable then we can make such a communication.