On a 2002 Lincoln LS has 4 o-2 sensors 2 forward the catalatic converter an 2 behind it. There location and how to install.

You want to replace all four?? Why??
There will be one mounted in each exhaust pipe, below the exhaust manifolds, another will be located near the forward edge of the converter and one located after the converter.
I need to ask you: are you getting codes for all these? Or just curious as to their locations?

I agree with captain rich, unless you are getting codes there is no sense in replacing them as some o-2 sensors can cost more than a hundred bucks a piece.