Charge traction Battery by Rolling down a Mountain

I have receintly purchase an inexpensive 01 prius with a presumably low or dead traction battery. (the car will not start at all even when the aux batt is jumped) there are No codes stored because the Aux battery was also dead. I have no history on how this happed as I bought the car at aution. My theory is the car was driven after it ran out of gas because the gas gage is also empty. I am hoping to get the 273v battery charged up enough to start the ICE to take over and codes can be reset for true diagnosis. But before I start charging the cells manually with a smart RC charger I wanted to know if It might work to tow the car to the top of a very long and tall hill/mountain nearby and roll down the hill with moderate breaking and try to charge the Battery that way at least enough to get the gas engine start. I suppose the car could be towed behind another car for a few miles for the same effect. Might this work and if so what gear and key position must I be in or any other things must I do for this to work?

 

OK, Can this be done while the battery is still in the car? Can I just remove the metal cover, unfasten the two Main Orange teminals from the center of the pack to open the circuit and start aplying 14.4 volts to two module at a time (19 times)....or is there too much in the way? Of course I will be wearing 1000v electrician's gloves. Are there any step by step links with pics for this? {{{By the way My lower display says WARNING and says PS, Main Battery(red), and a red carwith an ! on it.}{ the upper display has a Triangle with an ! in it}{ when I touch the screen to see the powerflow display I see the main Battery bar is about 1/5 way up}} Does any of that make sense? I am totally new to Prius's and when I get this one running it will be the first one I will ever have ridden in...Can you say NEWBIE??!!!