ZDepth-Maya/mental ray FumeFX 3.5.3 HowTo requested.

[rconover]

I've seen precious few rendered (Maya or Max) examples of FumeFX zdepth sequences on the web. Followed by an influx of "oh my gawds how did you do thats?!" in th comments section.
But no answer.

I gone over and over the UI I can't see any thing i can use in 3.5.3 to get this working.
How do I do it???!!!!