Well, thy have to spray %51 of your gun green.
http://www.landwarriorairsoft.com/upgrade-services-c21/lwa-two-tone-spray-service-rifle-p3496
they will mostly likely spray the stock, sights, and probably the front rail, but I have no idea so don't hold me to it. I heard that a strong air gun will do the job, and I imagine, if it is anything like the zero one airsoft paintjob, it will start coming off from the word go, but as I said, I have never actually used it so don't hold me to it. It seems to be a very expensive and not the best option gun to start off with. I know most people tell you this but honestly, If I were you I would get a G&G cm16 carbine as well. I have one as my first airsoft gun, and they are very easy to maintain, and have good accuracy and fps and rpm etc. Your choice, but if you have the money to spare, it would be a good choice IMO. hope that helps...