First you open your 3D mesh with MeshLab and convert it to Universal 3D (U3D) format. Meshlab then generates a snippet of code using the Latex document markup language. You include this code in your Latex document, compile, and voila: a PDF is created with the interactive 3D model built right in!
Check out the example PDF here: Laurana.pdf.
I wonder if it would be possible to export directly to U3D format from say Fledermaus or CARIS. This would necessitate some patches or hotfixes, but boy! what a powerful addition it would be.