This is how it's done while removed and in a vise. If you can duplicate the necessary forces while still attached, it might work.

1. Clamp or hold bottom of spring.
2. With a crescent wrench or similar, turn the top of the spring away from the spring's resting place.
3. Raise spring up and away from resting place (or if in a vise, lower the hinge).
4. Release wrench.