How to convert autodesk maya 2012 files to iges?
I created a quick tutorial here CR-X Poly to NURBS that shows my process. Download the PDF for the writeup.
The Maya model has to be a SUB-D based polygon model so not all models made in Maya will work well. There is also a module in Catia called Imagine and shape that will do the same type of conversion but the original model has to be a quad based subdivision model.
If you are building with NURBS geometry in Maya you just have to export as a .IGES. you may have to activate the .IGEs export option. That PDF explains how to do that as well.