I spent the long weekend switching over from underseat stearing to Windcheetah style club steering, which of course means I needed to do a front end alignment. My system is copied from Larry Varney's friend and mechanic Walt Smith. Walt graciously did an alignment for me at the 2005 Bentride.
The system uses two magnetic laser torpedo levels. Idealy its a two person job with the rider sitting on the trike (there's a little frame flex in all trikes). The other person lines up the targets first very close to the lasers and then again 20' to 30' away. I've found that an inch of toe in at 20-30 feet works pretty well.