First the FI’s have to be connected to a SAN device. Will be one of the below methods Brocade or Cisco SAN.
(Brocade) Setting up Brocade Switches between UCS FI’s and SAN Device
(Cisco) Smart Zoning and MDS
Now for setting up Boot Policies to point at a LUN on SAN device for boot.
High level video on UCS Boot from SAN to get the big picture across.
Cisco UCS Boot from SAN config by UCSGuru http://ucsguru.com/
As always UCSGuru breaks this topic down perfectly. Very thorough.