Easy way?

Bind the "<---" or "--->" (that's left or right arrow) as follows ONLY USING ONE ARROW KEY:

Toon 1. Nothing

Toon 2. Strafe right

Toon 3. Strafe left

Toon 4. Move backward.

Clear out all the old bindings prior to this. You'll have a spiffy little diamond formation.

Closing up: /follow focus.

You can always bind the opposite arrow to do the opposite movement, which should, in theory, close the formation back up. I run 5 like this, only I have 3 mages, a priest and paladin. I bound the RIGHT ARROW to:

Paladin (GL): nothing

Mage 1: strafe right

Mage 2: strafe left

Mage 3: nothing

Priest 1: move backward.

The end result is my paladin in front, the mages all in a row, and the priest, in the rear with the gear...

Hope this helps.