How about this?
Add or remove network cards (known as vmnics) to or from a vNetwork Distributed Switch (vDS) using these commands:
esxcfg-vswitch -Q vmnic -V dvPort_ID_of_vmnicdvSwitch # unlink/remove a vDS uplink
esxcfg-vswitch -P vmnic -V unused_dvPort_IDdvSwitch # add a vDS uplin
Note: f connectivity was lost when migrating management networking to a Distributed Switch, it may be necessary to remove or disable the existing management vmkernel interface and recreate it in a Standard vSwitch port group with the same IP configuration.
I've tested this in the local CLI and it works. Does this help you at all in building it into a PowerCLI function? This adds it to the correct Uplink.
The only problem with the above is that i have to specify an unused dvport_id and use SSH... which is a problem in its own.