There are some things that can be done with witches, using mods in Hexxit, but generally these rely on farming type mechanics. I feel the page should still be around but there is a lot of information still lacking from most of the pages.
Besides the farming mechanics, the biggest section would be a "How To Deal With Them" (or "Strategies" if you will) that could easily add additional content about any vanilla mob with Hexxit methods to dealing with mobs instead of just the standard.
Let me do some research into witches to see if they behave differently in Hexxit with other mobs, in other dimensions, etc. That way the page will have hexxit related content that pertains to the mod pack.
I'll also give some research into perhaps hexxit specific ways of dealing with them as well as hexxit specific ways for farming them, etc.
With all the mods in the mod pack I see no reason why such information couldn't possibly be there.