The script shown in that post uses the "showmirc" command from a DDE. You launch a new instance of mIRC, and it contacts the running process via DDE if it's running. It tells the running process to "come out from hiding" so-to-speak and then exits away so you should only have ONE running mIRC.
Re-read that thread and try that little script out, it should make mIRC re-appear like magic.
