Hold them in place with a piece of Sellotape/Scotch tape/Kapton tape/whatever tape you have handy. Put it over the hole, through the coils of the spring.
For some reason I never loose them, but my colleagues do! I think it's because they hold down the bed longer as they release it, so as it's twisting out of the mount, the springs are still compressed as they emerge from under the bed. So... ping! I tend to just twist the bed, and the tension is already released by the time the springs emerge.
Ian
RepRapPro tech support