You could re-activate inkey, when pressing Cursor Down like this:

if(key_cud){while(){wait(1);} inkey_active = 1;}

Didn't test it. If this is sufficient, depends also on your other needs.

http://www.puppenheim.org/
http://www.wuerfels-welt.de
Old Game Tutorial: http://www.puppenheim.org/MITutorial.zip
Free Game Editor: http://puppenheim.org/AlienalsWeihnachtsmann.zip
http://www.puppenheim.org/blender_starting_main_settings.txt