The Mongoose Spinward Marches supplement describes not only the Zhodani, but also the regions of the Marches which are either independent or are actual Zhodani client states. The Sword Worlds are heavily supported by the Consulate, but paradoxically they are almost as rabidly anti-Psi as the Imperium: the Daryen have a much more liberal attitude towards Psi, but they're supported by the Impies.
The best way of using Psi, in the OTU setting, is to emphasise the difference between life in the Imperium (e.g. the characters are on a world that suddenly gets subjected to a vicious anti-Psi, literal, witch hunt) and life outside it (e.g. on a world beyond the Imperium, where the locals have heard of Psionics, but aren't particularly bothered because they're all too busy just trying not to get killed by the local environment or starving to death).
As a supreme irony, of course, you could make all the really juicy Psi stories take place in the Imperium - controlled areas, where the anti - Psi fervour rages furiously, but the really weird stuff is going on all around them, right under their oblivious noses.
