You cant since your mIRC doesnt know that it was an omsg, mirc just messages all the users that has an op there no special thing behind to thats different then you opening a query to all the ops and saying Hello
some times it can know, but thats when people use /msg [b]@/+/%/&/~[b]#channel text. the ops or w/e will see the message in the channel window as a server notice, but i doubt that many people use this.
