Hi John,
there is no free solution. We have developp our own translator in/out with Catia V5, but you need a runtime license of Catia. I know Open Cascade Value Added Software were developping a solution, and it seems it needed also a runtime license of Catia V5 (have a look at http://www.opencascade.org/support/products/dataex/catia/). I don't know if the file format specifications are available.
Good Luck,
Commenter-1.