MergeSmoothing is a windows program that will read an FBX file and generate smoothing groups based on the normals of the mesh. It can read in earlier FBX versions and will output a 2012 FBX file. UDK wants smoothing groups and it wants version 2012 files. If both conditions are not met it will generate a warning message.
The Doom3 scripts for truespace 7.61 will read and write idtech 4 md5mesh and md5anim files.