Mostly, I think it's necessary to get creative.
It would be possible to use a secondary electric motor to drive the stock power steering pump, but the obvious problem with that is the additional draw on the batteries, and attendant decrease in range.
Some have experimented with the electric power steering systems used in late model "hybrid" cars from automakers.
Switching to full manual steering would be my first choice, although some vehicles may never have been produced with manual steering, so finding a rack or steering gear box without the hydraulics could be difficult. Converting a PS vehicle to accept the manual steering gear from a different model/make is the most difficult (probably something I'd try
)
Putting the PS pump on the tail shaft of a standard EV traction motor would leave you with no power assist when you need it most, times when the vehicle is standing still.
You could just build the EV without changing the steering at all, simply chuck as much of the PS equipment as possible, loop the input and output of the steering hydraulics together with a section of hose (do NOT cap those fittings off, you'll end up with locked steering, or the most difficult steering you could imagine) after filling the rack/gearbox with the proper fluid for your particular system. Of course, this assumes that you will be doing some body building to get your arms in shape for parallel parking!
Manual steering systems are usually of a lower ratio, meaning that less effort but more wheel twisting is necessary to turn the front wheels lock-to-lock. Power assisted steering gear is of a faster ratio, and will require more effort, although not as much as when the engine has died after you've removed all the extra bits.
