# Start service
get-vmhost hostname | get-vmhostservice | where-object {$_.key -eq "TSM-SSH"} | start-vmhostservice -confirm:$false

# Stop service
get-vmhost hostname | get-vmhostservice | where-object {$_.key -eq "TSM-SSH"} | start-vmhostservice -confirm:$false

# Set startup policy
# Automatic = Start automatically if any ports are open, and stop when all ports are closed
# On = Start and stop with host
# Off = Start and stop manually
get-vmhost hostname | get-vmhostservice | where-object {$_.key -eq "TSM-SSH"} | set-vmhostservice -policy "On"

references:

Manage ESXi SSH Using PowerCLI - Cloudy Future