In order to cluster Hyper-V virtual machines, you need the VMs to be on a shared storage which can be accessed by all cluster nodes; since you are using an iSCSI SAN, this should already be your case. You need to set up the cluster and then configure the VMs as cluster resources. In order to do this, you'll need to shut down the VMs, but if they are already stored on the SAN, you will not need to move them around.
Setting up a failover cluster can be tricky (pay special attention to your network setup), but it's by no means a terribly difficult task. These links should help:
Also, please note that in order to have a failover cluster on Windows systems, you need the nodes to be part of an Active Directory domain; if you don't have one, you'll need to set it up. And please don't use a virtual machine running on the same cluster as your domain controller... this is the worst thing you can do if you want your cluster to survive a reboot.