Your @search would need to be followed up by some form of a matchtext identifier to search for, like @search find-this-word, or something along those lines.
If that is the case, I would suggest just logging everything from #originalchannelname,(using mIRC's log) and then have your @search command be something like @search #whateverchannel-log-file typesearchword-here.
Then it could resort to that file, to search for that word. you can do that with wildcards
on *:TEXT:@search*:#2ndchannelname: {
scon -a $iif($network,networkname) msg #channeltogoto $read(original-channel-log-filename, s (or w), matchtext)
}
You would have to read up on the help file to find what switch works best for your application, there is s, r and w where w is a wildcard match. This might be a handy spot for regex evaluations (which I need to brush up on, so I won't get too deep with it)... Thats in the editor too, its not that rough to learn. Check it out.
The only trouble is if you specify a wildcard its going to return any random wildcard line that matches what the user is looking for. (*help* would return words including, help, helper, helpful... wildcard related) Use s for more specific match searches.