Most of them will have port 30004 open for their ingest domain, usually feed.domain.com. Thus you'd hook up socat to 127.0.0.1:30005 (i assume you run dump1090 or readsb locally as a decoder). And make socat send that to feed.adsb.lol:30004 and/or feed.airplanes.live:30004
If you're in a remote location, you don't need to worry about mlat-client as MLAT requires at least 4 receivers that receive common aircraft.
It looks like readsb is an evolution of dump1090 with potentially more features? I'll look into it when we consider reworking our software. For now I added a quick socat and I'll find out soon if it worked (no planes currently over Summit...). It would be nice if these websites advertised "Start feeding from your running dump1090 instance with socat tcp:localhost:30005 tcp:foo.bar:30004, here is a systemd service that does that."
edit: it worked! airplanes.live now tracking QTR28V from Seattle to Doha.
But to conserve bandwidth, it might make sense to send through a compressed ssh tunnel to something not in the middle of the Greenland ice sheet.