Upgrade specific clients--not entire OU/container

Is it possible to upgrade a specific sub-set of clients within a container/OU on SEPM? I do not want to upgrade all clients, but just a few.

Is there a way to upgrade these using PSEXEC silently and does anyone know the command line to do so?

Lastly, I don't want all the remote clients pulling over our WAN connection so is there a way to have clients pull from a local repository/website instead of the main SEPM?