All keys must be detectable, this is the GM developer's fault How going to use keys.
Keys that are detectable now (by SA's engine):
I Don't know if these are usable in SA-MP Or not.
OnFoot:
~k~~GO_LEFT~
~k~~GO_RIGHT~
~k~~GO_FORWARD~
~k~~GO_BACK~
~k~~PED_1RST_PERSON_LOOK_LEFT~
~k~~PED_1RST_PERSON_LOOK_RIGHT~
~k~~PED_1RST_PERSON_LOOK_UP~
~k~~PED_1RST_PERSON_LOOK_DOWN~
~k~~PED_ANSWER_PHONE~
~k~~PED_FIREWEAPON_ALT~
~k~~PED_CYCLE_WEAPON_LEFT~
~k~~PED_SNIPER_ZOOM_IN~
~k~~PED_LOCK_TARGET~
~k~~PED_CYCLE_WEAPON_RIGHT~
~k~~PED_SNIPER_ZOOM_OUT~
~k~~GROUP_CONTROL_FWD~
~k~~GROUP_CONTROL_BWD~
~k~~CONVERSATION_NO~
~k~~CONVERSATION_YES~
~k~~CAMERA_CHANGE_VIEW_ALL_SITUATIONS~
~k~~PED_JUMPING~
~k~~VEHICLE_ENTER_EXIT~
~k~~PED_SPRINT~
~k~~PED_FIREWEAPON~
~k~~PED_DUCK~
~k~~PED_LOOKBEHIND~
~k~~SNEAK_ABOUT~
~k~~PED_CYCLE_TARGET_LEFT~
~k~~PED_CYCLE_TARGET_RIGHT~
~k~~PED_CENTER_CAMERA_BEHIND_PLAYER~
InVehicle:
~k~~VEHICLE_STEERLEFT~
~k~~VEHICLE_STEERRIGHT~
~k~~GO_FORWARD~
~k~~GO_BACK~
~k~~VEHICLE_TURRETLEFT~
~k~~VEHICLE_TURRETRIGHT~
~k~~VEHICLE_TURRETUP~
~k~~VEHICLE_TURRETDOWN~
~k~~VEHICLE_FIREWEAPON_ALT~
~k~~VEHICLE_LOOKLEFT~
~k~~VEHICLE_HANDBRAKE~
~k~~VEHICLE_LOOKRIGHT~
~k~~VEHICLE_RADIO_STATION_UP~
~k~~VEHICLE_RADIO_STATION_DOWN~
~k~~CONVERSATION_NO~
~k~~CONVERSATION_YES~
~k~~CAMERA_CHANGE_VIEW_ALL_SITUATIONS~
~k~~VEHICLE_BRAKE~
~k~~VEHICLE_ENTER_EXIT~
~k~~VEHICLE_ACCELERATE~
~k~~VEHICLE_FIREWEAPON~
~k~~VEHICLE_HORN~
~k~~TOGGLE_SUBMISSIONS~
~k~~VEHICLE_LOOKBEHIND~
~k~~VEHICLE_MOUSELOOK~
Thanks to someone can post the values here.