Welcome Digg!
My little brother (the master of GTA: Vice City, he is better than me and I am 5 years older than him!

) found an easy way to complete this mission. Get a gun which fires lots of bullets (a machine gun or something like that) and run to the fire station. Go to the fire engine and shoot at it, even when it explodes just keep shooting. This will raise your chaos meter. You can do this on any wehicle but I find it easier with the fire engine as there is a fence which protects you from most of the cops.
Good Luck! <img src="/images/graemlins/smile.gif" alt="" />