My rules for hook were a regular attack, then an opposed ST roll. If the hooker won then the hooker optionally moved one hex back, the hookee moved one hex closer and maybe the hookee suffered some kind of DX penalty until the hooker's next attack. If the target was on a horse he fell off. In practice that's what hooks were for historically: pulling cavalry down among the dead men.
The downside is that really I don't think it would be used very much, except against cavalry. How often is it tactically valuable to drag someone from two hexes range to one? Other than when facing them on opposite sides of a pit.
Part of my solution to that was to have talents that meant some attacks were forced to be secondary. Your side's initiative die roll, modified by new talents, determined your right to attack. 1-6 was regular TFT rules so in the absence of special talents nothing changed. But if you had a talent that pushed it down below 1 you got a bonus secondary attack. So a guy with a sword and a shield might be able to attack with both, or a guy with a halberd might be permitted one hack and one hook, or a swordsman might get a stab and a pommel strike, or somebody might be allowed to stab and also trip, if they had an appropriate talent and/or the initiative die was their friend. Under other circumstances, when the dice were not their friend and their enemy had a good defensive talent, the modified initiative might go above 6 and the attacker might only get to make a secondary attack, not a primary. But this is all a dramatic change, slightly fiddly, and primarily done for reasons that had nothing to do with hooks.
Otherwise it's hard to make hooks relevant enough to be worth a whole action.