Mwa, A particle script is in essence the same as a shader, only it's for particles. Just take a good look at some particle scripts that are crazy
(Uncreation!) and you will get a hang of it. Editor-wise, they are just placed in the map as a misc_particlesystem orso, look in the entities.def file for some more info on that. Writing the particle scripts is a totally different matter though:), according to Catalyc they 'randomly break things', hehe.