This is done by adjusting the length of both of the parallel (radius) arms, correct? Ingalls actually sells an arm:
I'm guessing that you use the toe adjustment to adjust the length of the other stock arm?
The other option is to make your own, like Greg Amy did:
I'm guessing with both arms you would get more adjustability and stronger arms? Greg also used heim joints there, while the ingalls uses either rubber or polyurethan. How would the NVH be using the Heim joints? Also, I have read that the trailing arm is really not needed to locate the knuckle. Its there just to add strength. So, with stronger tubular arms, would it be possible to completely ditch the trailing arm since it binds?
Another advantage to this that steve f pointed out to me is that you could take away negative camber by relocating the holes on the strut ears to give you more strut to wheel clearance, then get the negative camber back by adjusting the parallel arms.
I was also wondering how changing the length of the parallel arms changes other aspects of the suspension geometry, like roll center, scrub, etc.