Did you ever get a resolution to this?  I too would like to be able to pass authentication via vmware-rc command line.  Though -u -p are supposed to work, it doesn't.

I note the Boomerang utility is able to passthrough the authentication, with the command line:

vmware-vmrc.exe -h (servername) -M (vmid) -u (username) -P

And presumably that's going through an API as described here. 

But that doesn't help me from a command line.  Better still would be able to have a passthrough authentication like you can have for the VI Client.