Yes I think "terribly written" is being polite. I since found another HP document (4AA3-6918ENW.pdf if it helps anyone) which explains it in a lot more detail, and it is pretty much as vSphere 4 was, multple VMKernels each bound to a single pNIC.
Incidentally does anyone know if:
a) an upgrade from 4.1 to 5.0 U1 via an Update Manager ISO keeps your iSCSI config?
b) there are any issues upgrading 4.1 which was installed from a regular ISO to 5.0 U1 using the HP ISO from the VMware website?
Thanks.