Correct me if I`m wrong, but this setup is made to be able to use every one of your chars as a main right?

Because if that`s so, I think I did it with less work(script), haven`t gone trough all your scripting yet so I`m not 100% sure. But the way I did it I can change to any char to set it as a main, just by one keyclick and I can still use the same follow and assist macro.
In general you are correct, it is a way of using every char as you're main.
The paradigma of the ftl-setup is, that whatever WoW-window has the focus, is your 'main','master','active-played' toon (or how you wan't to call it).
The beauty of a 'true' ftl-setup is that you have not to press any special button you wouldn't press in your gameplay to promote the 'leaderchange'.
Instead of pressing a special button, the 'leader-change' is simply promoted by the action itself (like casting a Lightning bolt), using hotstrings and appropriate macros.

This means, that you can do the following (image the typical 5-shaman group for simlicity):
1. On your ToonA, target an enemy (enemyA)
2. Press '2' on ToonA, which is bound to Lightning Bolt on all Toons => all Toons fire a LB on EnemyA
3. Click in the window of ToonC (so ToonC is now you 'active played)
4. Target an enemy with ToonC (say EnemyB)
5. Press '2' => All cast LB on EnemyB
6. Click in the window of ToonA
4. Press '2' => All cast LB on EnemyA (because As Target remains)
...

..so you see, you have never directly 'promote' someone to the leader, its all done implicit.
This allows very intuitive and fast leader switching, in addition with not using target und focus for defining who the leader is.
For the general idea and more infos on the ftl, you can look at: http://www.dual-boxing.com/wiki/inde...aderless_Setup

If you have a better/simpler solution, feel free to share it, I would be very interrested!