In polar coordinates, the point
$(-r,\theta)$ is the same as
$(r,\theta+\pi)$, so you'll need to do a bit of shifting if you want negative radial values (though I would no longer term it polar coordinates).
Anyway:
ListPolarPlot[{}, PolarAxes -> True, PolarAxesOrigin -> {?/2, 0},
PolarTicks -> {{#, Mod[(?/2 - #)/?, 2] 180 °} & /@ Range[0, 2 ? - ?/12, ?/12], Automatic}]