You can convert the camera's pan to a direction, and multiply the direction by the key:

VECTOR to;
var speed_value;
vec_for_angle(to, camera.pan);
vec_scale(to, key_a * speed_value);

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