Changing Particle Render Mode Mesh

This is for Javascript, I was able to change the Particle effect renderer mode from Billboard to Mesh. I've got:

 function Start ()
 {
 var Particleffect = ParticleHit.GetComponent(ParticleSystemRenderer);
 Particleffect.renderMode = ParticleSystemRenderMode.Mesh;
 }

So how do I change the Mesh Object of the Particle Render Mode?