This isn't correct. If you put the looper last in the chain, it will always sum what's coming into it and output it as a dual mono signal. So any panning you have in your tones will disappear. There's not really a good way to pan the looper. You can do some sort of separation by using the FX loop block cleverly, but it's not a very good solution because it requires modifying every patch that you want to use it in.

Placing the Looper in PRE postion means the looper will record the dry, unprocessed tone directly from the inputs. The recording is done before the amp/fx are applied to the incoming signal. This is useful when you want to experiment with different presets while playing back the looped recording of the dry signal. You can test out different amps/fx instantaneously without having to play the guitar.

Placing the Looper in POST position means that the looper will record the fully processed signal - all amp/fx in the preset are applied to the recording. This is useful when you want to, for instance, play a lead solo on top of playback of a processed rhythm guitar recording.