Have just had to do this and after a lot of digging and coming across your 0 reply post!
Firstly I automated the set up a vSwitch with vmkernel portgroups each with single bound physical adapter.
Then enabled s.w iSCSI using UpdateSoftwareInternetScsiEnabled API
Once enabled, for my environment I set up iSCSI IQN required, and add targets
I then use QueryCandiateNics to look through devices I can use for binding. Up to you to filter through the list an return only the ones that comply as far as I can see.
It returns iSCSIPortInfo list.
From this list, extract the ones that comply - I just looked at portgroupname I know I have set up.
Then call BindVnic passing in the adapter name (e.g. vmhba41) and the iSCSIPortInfo.vnicDevice
et voila... my NICs were bound as if I had done it through the UI
