First of all, what do you mean exactly by archiving ?
Secondly, your question should better be asked on the Sun IDM forum. Anyway, I would say there's nothing out of the box, but you could
develop a workflow to do such a task.
Some customers just disable the users without moving or archiving them. Others move them to a new DIT (directory branch) or a new directory.
As you understand, there're many options to accomplish this.
Basically, why just disabling the users isn't enough for you ? (assuming you already have a backup an archive and backup strategy for your regular
users at least)