Dude, go buy a set of metric wrenches for $6.99 and do the job right the first time. Not worth the hassle and time wasted trying to monkey around with improper tools and perhaps the frustration of destroying your perfectly good parts. Then having to spend even more money and time buying replacement parts AND the proper tools later. You'll need a 9/16" or 15mm wrench to work on the pedals:



And remember that the left-pedal is left-hand thread. You turn it clockwise to loosen.