If you are working with unity you can try the "strumpy shader editor" its free. The only problem is that it is only supported til unity 3.5. But the compiled shaders should still work with unity 4.
Depending on the version, I have a few cgfx/directx shaders that are simple to set up and do their job. I don't think there is a way to export them for Unity/UDK though, so you might be better off writing your own in order to make sure they're using the same math.
You can try it with the Ultimap_preview shader. Just open the rendertree and then choose "nodes" -> "realtime" -> "ultimap_preview" it has a color, normal, specular and ambient imput. The ultimap preview shader works great if you bake directly inside softimage. I haven´t tested it with xNormal Normalmaps or other sources.…