Getting the multipathing policy using PowerCLI is a very simple an straight-forward process that can be done with a few commands.
I test this procedure in the past with ESX/ESXi 3.5 and 4.0.
Get the multipahing policy
Change the policy from fixed to round-robin
We are going to change the policy for the LUN 12.
Finally check the new configuration
If you look closely at the last line will see that the value has change from