If the repeater is not a stand-along System Fusion repeater and has a connection to the WIRES_X system (either via an RF node or direct) then you can use the WIRES-X function on your radio to connect to a room (America's Link) on that repeater.
Let me be clear as room naming seems to be very loose . IF the room to which you want to connect is a WIRE-X room maintained on a Yaesu server and not an FCS room maintained on PiStar servers, then what I wrote above holds true. IF the room is an FCS room, then that can only be reached via an MMDVM system