Calling All Stereo Heads, Help!

they used to bridge F and R on old Pioneers. ie. "for 4 speakers use this, for 2 speakers, use that..." try and use each hot lead as the positive channel of a 4spkr system and bring all grounds back to radio ground. I cant recall if there was a bridge switch on the radio to tell it to use 2 hots per channel. Someone confirm this before he blows his system please.......
Will try today thanks
Martin