How to access Particle System Collision to change at runtime

As the question states, how does one access a particle system’s collision variables at run time through c#? I’ve noticed some of the variables are accessible meanwhile others are not listed.

Any suggestions?

Thanks.

What variables are you looking for?

http://docs.unity3d.com/ScriptReference/MonoBehaviour.OnParticleCollision.html

http://docs.unity3d.com/ScriptReference/ParticleSystem.CollisionEvent.html