As far as I recall, this was from one of their blog or something like that.
Well, I think I never had a chance to see something like this in the game so far. Because cavalry is always either too disorganized or distracted with other surrounding people. I think "unit targeting" would fix this lameness - or at least feeling of lameness. I don't think it's rocket science either. Select cavalry - Hover your indicator flag to the enemy squad(Even show a target icon, something like
use icon on machinery) - F3 and they will lock to that particular squad.
If you just select your cavalry, and F3 without specifying anything else, let them charge as usual.
That might sound to surreal but there is actually a mod like this - I guess it was in RTS mod. So it's pretty much doable.