This is called an "unlit" shading model Graphic3d_TOSM_UNLIT, which can be set via Graphic3d_Aspects::SetShadingModel() property. Here is a sample Draw Harness script:
pload MODELING VISUALIZATION
psphere s 1
vinit View1
vdisplay -dispMode 1 s
vfit
vaspects s -shadingModel UNLIT -color RED