Although it's good to have separate switches for iSCSI, it actually depends on the size of your environment (I/O requirements) and the current switches you have in place (port buffer size, Jumbo Frame support, flow control capable, ...), whether it is ok to simply use a dedicated VLAN on them. I've configured both in my customer's environments, and didn't have any issues with VMware's software iSCSI so far.
Assuming you are talking about software iSCSI, there's nothing special you need to configure on the network adapters themselves. It's basically configuring the IP addresses on the VMkernel port groups, setting the failover policies, and - if you are going to use Jumbo Frams - setting the MTU on the vSwitch as well as on the port groups.
André