You mean with UVLayout? I don't really have an issue with authoring lightmap layouts manually in general and yes, you can get UVL layouts into Unity UV2 by moving results of UVLayout work into the second channel before exporting the final file. But the question of the thread is whether there exists an automated way to get…
Are you adjusting the Flatten angle at all? For lightmap UVs I usually set the angle to 60 or so, to make the islands larger and more contiguous. UVLayout from Headus is a lot better at packing UVs than Max, but it's not free. However many people love it for unwrapping. Worth a look.
@Eric Chadwick Sorry for the late reply: I do own UVLayout, can you elaborate on the automated workflow it enables? I have always used it for manual unwrapping of delicate hardsurface and organic objects (fancy manual pelts and all that), but I'm not aware of any way to generate full layouts there automatically.
Oh, that's an interesting idea. Strip texturing might have some undesirable seams where lightmap UVs shouldn't, but islands from it should be a lot better than ones generated by Flatten mapping (wrapping around objects and such), so packing them might give a nice result. This is the first time I'm hearing that IPackThat…