Implementing Out of Process COM Server, one server process per calling process

Question

I need to implement an out-of-process com server which initiates a com process per client process. An answer to this same question suggests using different GUID's for each server.

My COM server is ATL & I invoke it simple by CoCreateInstance. The question is what are the steps for implementing the suggestion in above link? At what stage should CoRegisterClassObject be called (Currently it isn't called at all)? Would it replace some existing registration? How will the client & server coordinate generated GUID: the server(client) should get the client(server) pid somehow.

Also I would like to hear if there are other approaches for solving the one server process per calling process issue.

EDIT: BTW, if I run one process from within VS debugger and 2nd by dbl-click, two server processes are created!