if you mean the actual mod, they'll be using CPMA vq3 for sure.
but since there were no restrictions about the client for the qualifiers afaik, they might use cnq3.exe instead of quake3.exe

they're using a specialised .exe that fucks with logitech mice, just ask rapha or killsen about it
i saw it on here a while back, used it for a few days and didn't notice much, but i guess it locks out some cvars or something