Project64k has fully implemented Kailera support, as does Nemu 0.8. The next release of 1964 should as well, but 1964 0.8.5 does not have functional Kailera.
you must download the server software for Kaillera to run http://www.kaillera.com/ one of the computers must run the server(i think best is the one with the best ping) and then everybody needs the ip of that server for faster joining