I would guess he wants to have a "power pack" or "pony engine" on the scraper, and electric over hydraulic controls. I think it could be done, but it will not be cheap. Bang-bang valves would be the simplest, but control would not be very precise. Proportional valves would give the best control, but how to rig it up is beyond my pay grade. I use a proportional valve to run auto-grade on my scraper, but it requires software and a machine control (DAC) box to operate.Do you mean live hydraulics to the scraper with electric control valves on the scraper? If so, no problem.
Or do you mean an electric drive hydraulic pump on the scraper? I'm with Welder Dave on this one. It takes 60 amps of 12V to get 1 hp worth of work, where 1gpm of hydraulics at 1700psi is 1 hp.
If you are looking for off-the-wall solutions for truly self-contained, how about a ground drive hydraulic pump and a large accumulator?