  We report on the resonant optical pumping of the |\pm1> spin states of a
single Mn dopant in an InAs/GaAs quantum dot embedded itself in a charge
tuneable device. The experiment relies on a "W" scheme of transitions reached
when a suitable longitudinal magnetic field is applied. The optical pumping is
achieved via the resonant excitation of the central {\Lambda} system at the
neutral exciton X0 energy. For a specific gate voltage, the red-shifted
photoluminescence of the charged exciton X- is observed, which allows
non-destructive readout of the spin polarization. An arbitrary spin preparation
in the |+1> or |-1> state characterized by a polarization near or above 50% is
evidenced.
