There’s so many ways to create a ZDepth Pass in 3ds max, thinking about it I will show you an easy way to create a ZDepth Pass using the override technique.
I always use this technique in my workflow, this process is easy and quick to setup and very fast to render the sequence files as well.
I hope this tutorial help you in your next project. Enjoy!
tutorial & download: http://www.hmelo.com/tutorials/zdepth/zdepth.html