Makers of good brake-pad with mounting hardware - such as Kool Stop - have beveled washers. By turning these washers on their axis, they will change the angle that the pads with hit the rims. A little toe-in is easy and doesn't require twisting any caliper-arms. Doing this the first time is accomplished by trial & error. If you remember what the correct configuration looks like, the next time will be a breeze.