You do not need to set anything up on the main box. But best to set it up so it has a fixed IP address. I leave my receivers on DHCP and have assigned/reserved IP address on the router. You must have a free tuner available on the main receiver, otherwise you can only watch what is on the same frequencies. There is no indication of what is/isn't available.
On client receiver, install RCSC plugin, enter IP address of host receiver, slect teh bouquets you want to download. You then select the channels you want.