Actually quite a few folks have already engineered setups like this for battery electric vehicles, since a lot of parts like brakes, air conditioning, vacuum pumps, and power steering require constant rotary power inputs which you don't have on an electric vehicle. The mechanical belt linkages are normally not preferred, since they take up space, vibrate, make noise and are generally troublesome. Mostly they go right to DC electric driven components for vacuum, water pump, etc. The exception is the compressor for A/C, usually that is driven by a closely coupled belt or a direct shaft coupling, but it eats a lot of power. Hope these links help!
See:
http://www.california.com/~eagle/figs/vacpump/vac.html
http://www.austinev.org/evalbum/
http://www.metricmind.com/water.htm
http://www.metricmind.com/pump.htm