This will enable VMotion on a VMKernel port. I am writing this one because it changed between verisons of ESX. This command uses the very useful vimsh.
ESX 3.0.x:
vimsh -n -e "/hostsvc/vmotion/vnic_set portgroup2"
portgroup# - Determined by the order of portgroup creation. The system automatically makes one to begin with.
ESX 3.5:
vimsh -n -e "/hostsvc/vmotion/vnic_set vmk0"
vmk# - Determined by the order of the VMKernel port creation. The first one created is '0'.
