Integrating thugs with normal troops is largely a matter of matching up movement rates. You can also place them sort of "in the middle" of squads, so the thug can't rush ahead easily, but it means he can't get into the melee until a few guys have died.
But Bane Lords are not going to cooperate well with C'tissian infantry, with a Chill aura, and Cold Blooded troops. You will mostly want to use squads of Bane Lords operating without army support, as sweepers, perhaps with a buffing mage or three. Then have the infantry clean up and siege castles.
Of course, if you were talking about having the Bane Lords "blend in" to a horde of skelly spam, that's a different biscuit. Placed just ahead of the mages on Hold and Attack, you keep the Chill away from the casters, but the first round of skellies should get up ahead of the Bane Lords by the time they engage. This also means any missile fire focuses on your thugs, rather than on your casters, so you get bonus points.
