Symmetric Multi-Processing Fault Tolerance (SMP-FT) is a new feature that was introduced in vSphere 6.0 which allows you to enable FT against a Virtual Machine with up to 4 vCPU. In addition to this new functionality, a new vSphere 6.0 API was also introduced to allow customers to easily manage this from an Automation standpoint. Previously, the CreateSecondaryVM_Task() vSphere API was used to enable Uni-Processing Fault Tolerance (UP-FT). With SMP-FT, there is a now a new vSphere API method called CreateSecondaryVMEx_Task() which supports a few additional parameters which is now required for enabling FT (UP-FT & SMP-FT) compared to the old "Legacy FT" mode.

Disclaimer: The example script is meant to be used for educational purposes. Please ensure proper testing is done if you decide to use it for Production environments.

I have created a small PowerCLI script called Set-FT.ps1 which exercises this new vSphere 6.0 API and below are examples on how to turn on or off SMP-FT for a VM:
Turning On SMP-FT

Set-FT -vmname "SMP-VM" -Operation on -Datastore "vsanDatastore" -Vmhost "vesxi60-5.primp-industries.com"

Turning off SMP-FT

Set-FT -vmname "SMP-VM" -Operation off -Datastore "vsanDatastore" -Vmhost "vesxi60-5.primp-industries.com"