The idea of this tactic is to move fast with your horsearchers on the centre (and left) and with your cataphracts on the right (or left, whichever you prefer). This will cause the enemy formation to completely fall into dissaray. Cataphracts (or horce archers) then kill the enemy general and the game is over for them.
Thing to remember with this tactic is that fast movement is very important and I strongly recomment that all of your heavy cavalry are at one side.
An enemy that expects that this tactic is implimented should move all of their heavy cavalry behind their infantry and try to push back the cavalry charge when it comes. But even if the cavalry (elephant) charge fails the horse arhers can cause much damage to the enemy. Anyway this sort of tactic gives a good advantage to a cavalry army I think.
.. works very well especially against the computer and I havent lost a single battle by using it.