At a minimum, you will need an additional port per device.
These are all on the same network (and switch), but they will have to be on their own fabric. A fabric consists of one of the available ports (and the iSCSI card), the switch, and the port on the far end storgae device. Each of your Servers need to have at least two fabrics set up for MPIO to work.
Start by installing the iSCSI cards in at least two ports per device. Next, install the card driver and then the MPIO software for each server.
Setting up an iSCSI san for MS SQL Server (some good tips in general):
http://msdn.microsoft.com/en-us/library/bb649502(SQL.90).aspx#_Toc169804521A QLogic primer on SAN side setup (shows WWName use and contains some good tips):
http://www.qlogic.com/SiteCollectionDocuments/Education_and_Resource/whitepapers/whitepaper1/qlogic_wizard_web.pdfAs you install the iSCSI cards, note the WWName of each card (essentially the MAC type identifier). Use the WWName of the card to configure the switch for MPIO traffic. You will have to identify which WWName is for which server fabric (depending on your switch model the process may vary).
After the server has been set up and the switch has been configured, all you need to do is configure the storage end device for MPIO.