It is shown that the spin orientation and polarization of an exciton confined in a QD can be controlled via two-photon transitions, by virtually coupling the single-exciton states to the detuned ground and biexciton states. Furthermore, phonon-induced dephasing leading to loss of fidelity in the two-photon optical control schemes is studied. Exciton spin flip can be performed with errors as low as 10⁻³.