Well blender has a plug-in that does and milkshape can not sure about any other programs, but I'm not sure how to import a sketch-up file, I think that blender can do it with a plug-in what file formats can it export I haven't used it in forever but I think it's only the one. I'm probably not the best person to ask, you'll need to have someone else who's done it help you probably though I've never done it myself I just know you can't export it directly to .dts.