ZnSe/GaAs(001) interfaces were fabricated through molecular beam epitaxy by predosing the GaAs(001)2x4 surface with ordered monolayers of Se or Zn, prior to ZnSe growth in stoichiometric growth conditions. We performed the predosing at room temperature (RT) and achieved ZnSe epitaxial overgrowth at RT to minimize desorption of the adsorbed species and minimize interdiffusion. In situ synchrotron radiation photoemission studies indicate that Se-predosing results in valence band offsets as low as 0.40+/-0.05 eV, and that Zn-predosing yields valence band offsets as high as 1.01+/-0.05 eV.