I know exactly what you are talking about, and have pulled it off many times. Here's the key -- you've got to negotiate it behind the scenes, and only go to the council once everyone is in agreement and will vote "yes". That's where most people screw up. They go to the council meeting and plead their case and try to negotiate it in public. You should never negotiate anything in public -- you'll never win. But in private, you can cut deals with the various councilmen to appease their personal concerns, and then the public meeting is merely a formality.
It took me a few years to learn this lesson. I have never won a case in which I try to negotiate it in public. I have won 50% of those negotiated in private.