According to the documentation on the Microsat website, the KISS (and APRS-IS simple server) ports are only available over TCP/IP (the Ethernet connection), not via the serial ports reserved for weather stations and GPS receivers.
So you would use the KISS-over-TCP port type to connect to the documented port number (I don't know the exact number, but I'm guessing port 8001 because that's what DireWolf and AGWPE use) at whatever IP address is assigned to the WX3in1 on your LAN. Alternatively, you could use the APRS-IS port type to connect to the "simple server" port just as if you were connecting directly to the APRS-IS backbone.?
Hopefully, the Microsat author would be able to provide more specific information.
Andrew, KA2DDO
author of YAAC
