I'll chime in and give a solution too. I've had good results with this, by creating a small Render to Texture actor placed at the same position/rotation as the flashlight, and then giving it a process to return the Z-Depth. So basically you've got a small texture that now shows rays from the flashlight point outwards. You…
UDK is just plain missing the kind of features required to get this kind of thing working. I've personally never managed to come up with a decent solution, although I suspect it may be possible to attempt such a thing using post process.