i have yet to find anyone with the standard abs set up who has been able to succesfully bleed their brakes in the way you mentioned

the pump pressurises the system, the brake pedal allows the opening of the rear rbake curcit once it sees power via the electrics, the rear brakes work, i fail to see how this can be replicated by someone forcing air into the resivour and then opening the bleed nipples as you still have to press the pedal to get any fluid to get out AND have the ingition on to open the valves

if i'm wrong then fair enough, but 12 years worth of people trying this way and failing miserably tell me that may not be the case