How do I get the UserSession of each VC that is part of the linked VC?

I have a VC that is in linked mode.  Example, vCenter Server A and vCenter Server B are in linked mode.  If I write a simple java client that does vimport.login given the username/password on vCenter Server A, how do I get the UserSession on vCenter Server B?  The main purpose is that I want to create a CustomValue on both VCs.