I know this was from a long time ago in the thread, but for people who are having problems with their quads turning into tris in Max before importing into ZBrush the polyboost plugin has a nice little one button script that fixes this very thing called Quadrify. Check it out at www.polyboost.com
Additionally over at www.scriptspot.com there is a free plugin called quadtriangulate.
You can get it here.
http://www.scriptspot.com/scripts/web_upload/Gene%20Crucean/quadrangulate.mzp
Just thought you guys would like to know.