dinamic ACLs

Hi all,
I would to implement some sort of dinamic ACL lists.
This is my wish:
I can write my acl lists as files and modify them later by a demon.
How (and when) Squid read these files ??? At startup or every
connections (I don't think so......).
How can I force squid to re-read his acl files without a consistent loss
of performances ??

-- 
Max Liccardo                    mliccardo@tim.it   (at work)
                                mliccardo@mclink.it   (at home)
                                "..fatti non foste per viver come bruti,
                                  ma per seguir virtute e cAnoscenza .."