6.1 addon?

My Receiver is 5.1 ...Can I use a seperate Processor or Receiver with Dolby 3 stereo to get 6.1 accurately?...have any good recommendations without breaking 200.00?...will a sub and an Equilizer hooked to this 6.1 on the rear channels be an advantage also?...I was reading on a way to connect the rear pre-amp outputs from my 5.1 into a receiver or processor with dolby 3 stereo...is this the right way?
From a 5.1 processor, connect the left and right surround outputs to a Pro Logic processor left and right input. Set it to Dolby 3 and use the left front,center,and right front outputs on the PL processor for the 3 or 4 side(surround) and back speakers. This will give you a simulated 6.1 but not true 6.1.
Actually, I beleive parasound made a decoder for this exact situation. You connected it like Nerspellsner said, but it would give you the actual 6.1 output for the rear center