Well I havent broken a tank yet and I have made 3 of them ( working on my 4th this afternoon ). I take a hacksaw and cut through the plastic trim about twice on each side, then carefully work the pieces with my fingers pulling it off. With some patience, strong hands and luck it will turn out fine. Stay away from using any other tools such as pliers or screwdrivers to pry the trim off as that is when you will break the glass. Also remember the edges under the trim usually still have a pretty sharp edge so sand them after the additional silicon is taken off with a razor blade. I will take pics of my work this afternoon and probably post on Monday.
Rob