NSX does not offer Network & Security configuration via CLI (LB included).
The 2 options are:
. UI
. API
For the API you can find a dedicated API documentation.
Note: If you like PowerCLI, there is also an open project to drive NSX via PowerCLI called PowerNSX https://github.com/vmware/powernsx.
There was a dedicated session at the last VMworld 2016: NET7701.
Thanks,
Dimitri
