This seems like such a simple feature that is built into the other 3d apps usually as a "Triangulate" button you can press for instant results. I find it maddening that Max still doesnt have this basic feature.
I know this workaround: Grab the faces you want, detatch them, turn to mesh with limit poly size to 3, then turn back to poly and reattach and weld verts. This works but can be tedius, especially since I and my coworkers sometimes have to do it on many many objects, and the welding if not careful can cause some unintended welding of verts.
I've even heard a couple other workarounds like converting the selection to verts and using connect, but this will triangulate more than just the selected faces so it is no good. (Works good on an entire mesh)
I have yet to find a single script on the net that addresses this issue. Looked through scriptspot, searching here on CGTalk, Google, etc. (About every 6 months I go on a quest to find it, only to be disapointed). Most of the scripts I've found either add geometry (turning a quad into 4 tris) or do other odd things.
The reason we need it is we export quads and tris for our game engine on the Nintendo DS. The DS will actually render quads unless they are non-coplanar (bent), so we need to triangulate non-coplanar quads. We already have tools so select non-coplanar faces, so this what we want to triangulate. Triangulating all the faces would be bad since the DS renders quads a bit better.
Anyone ever seen an example, script or have any idea how this can be done?