The cairo_ps_surface_dsc_* function were added in 2006 for cairo 1.2.0:
http://cgit.freedesktop.org/cairo/commit/src/cairo-ps-surface.c?id=09dfd6c3

I could find any trace of a cairo_ps_surface_begin_setup function anywhere, even going back to cairo 1.0.0. Unless I'm mistaken, the only place it appears is in documentation in the above commit.