who has a fully working CrossfactionBG script?

Sorry for my bad english

Lillecarl made one for TrinityCore a while ago.

You can check it out here @ https://github.com/Lillecarl/TrinityCore/commits/master

As far as i know Lillecarl  has made it already for MangosOne (or even partialy or complete for old OC)
Maybe try to ask, i don't know how complete it was, but it should be much easyer to port from there then from TC2