not quite sure of the query on this...can you provision ISCSI LUNS to an ESXi host for datastore provisioning i assume?
then if that is the question, then I would say yes of course, and would expect that is fully supported by NetApp, is the concern no Virtual Centre and VSC and does that give you a problem?
again no, NetApp can of course just be deployed with the protocols and will be fully supported, the software suite is there to make life easier and provide better value to the solution.
please re-post if i've misunderstood or you need more help...