I have successfully created a LANDesk Boot WIM using WIndowsPE 3.0. (and added ADSI components so that you can script domain functoinality)
I've been meanign to write-up an article on doing it but it's not a real simple process, as it involves not just copying files, but also adding services, and modifying the WinPE registry hives.
If there's people out there with interest, I will write something up later this week or weekend.
Also interested, as I'm sure LANDesk would be as well... but only if you have the time!
But I am probably more interested in learning the differences between the versions (especially how it may relate to LANDesk).
Have you written your doc on implementing WAIK3 ?