Try something like this:

if(key_a)
{
while(key_a){wait(1);}
vec_lerp(my.pan, vector(my.pan, 0, my.roll), my.pan, 0.1);
}

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