In answer to Dave's reply to reprogramming the FCUs to not have the autoflap function at flaps 25 and 30.
I would guess it would be possible to reprogram the FCUs so they could work in the sense you describe but without knowing the internal workings of the FCU I wouldn't like to speculate on what could be possible.
I have looked at the wiring diagrams for the T/R and Flap Systems and it is fairly simple in that when either T/R1+4 or 2+3 are detected unstowed(not deployed) and aircraft on the ground the Group A flaps retract. The input to the FCU from the T/R position system is a ground that is switched by a relay so I would imagine that Boeing would look at interlock circuit involving relays with some input from another source such as the throttle lever as previously suggested.
Hope this is of interest.