According to the Source Code, Movement Components are already Blueprintable:
UCLASS(ClassGroup=Movement, abstract, BlueprintType)
class ENGINE_API UMovementComponent : public UActorComponent
This is in 4.12.
EDIT: Actually maybe the meta has to be ‘Blueprintable’ instead of ‘BlueprintType’ (which is for enums / structs). This might actually just be a typo…