All you have to do is to pipe the corresponding message to ezmlm-send DIR. Messages awaiting moderation are kept in DIR/mod/pending/. To find a particular file, grep the contents. Thus, to find a file from ‘firstname.lastname@example.org’, try:
% grep 'user@host\.dom' DIR/mod/pending/*
(Depending on your setup, you may not have to escape the period.) Check the files for the owner execute (‘x’) bit. It is set on all messages queued successfully. Ignore other files!
To then accept the message (change the ezmlm-send(1) path if you've installed in a non-default directory):
% cat DIR/mod/pending/filename \ % /usr/local/bin/ezmlm/ezmlm-send DIR
% ezmlm-accept ~joe/SOS ~joe/SOS/pending/*
will accept all messages in the queue of the list in ~joe/SOS/.