Mike,
By default, the MBEX password if "admin", at the first time that you get into MBEX you will requested to changed it. If you let it unchanged (i.e. default factory), SCCM can automatically connect and start the provision process (assuming that you have all infrastructure requirements, such as DHCP with option 15, valid 3rd party certificate, DNS, etc.). Also a very common issue that I observed on many vPro activations, is that Windows Firewall on client side block communication from SCCM to vPro. The best way to see is look into amtopmgr.log that can give a good clue where the provision process is stuck.
Best Regards!
-Bruno Domingues