Ah, Well yesterday I finally found the DFX2 Lan patch download from a DFX2 Facebook Fan Group, who use it to play through tunngle.
All it seems to be is a modified joint ops typhoon rising game.exe with modified menus to display a "Lan option" rather than a "Multiplayer option" which starts up novaworld.
I tested adding some custom DFX2 maps and they all worked. However, I tried adding a DXF2 mod such as the Black Ops 1.6 mod and several parts of the mod didn't work such as the new weapons. My theory for why the mod's stuff didn't all work is that perhaps it is caused by starting the DFX2 with a jointops.exe.