Vray Metalballs -- how to choose only a particular event?

[davision]

I want to use Vray Metalballs on an event within the particle system, but not the whole system. How can I limit it to the event I choose?

[Dave_Wortley]

It's annoyingly complicated but you can do it via script. The BlobMesh has the ability to pick PFlow Events, something that the VRay MetaBalls could use too.

$.positive_particles = #($'PF Source 001->Event 002')