Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Texture
ARTSHADER_TEXTURE
Parameter: Use Bump
ARTSHADER_BUMP
Parameter: Space
ARTSHADER_SPACE
Parameter: Scale
ARTSHADER_SCALE
Parameter: Rotate
ARTSHADER_ROTATE
Parameter: Scale U
ARTSHADER_SCALE_U
Parameter: Scale V
ARTSHADER_SCALE_V
Parameter: Shadows
ARTSHADER_SHADOW
Parameter: Texture
ARTSHADER_SHADOW_TEXTURE
Parameter: Backface
ARTSHADER_BACKFACE
Parameter: Texture
ARTSHADER_BACKFACE_TEXTURE