Every time I join a channel, mIRC does /names and shows me every user in the channel.
Every time you join a channel, the IRC server automatically sends you the names list of the channel. This is part of the IRC protocol, and there is nothing that mIRC can do to stop this. So searching for a /names command in your scripts will not help at all.
By default, mIRC hides these incoming names lists on join, and this can be controlled by the option that KindOne mentioned. If that option has no effect for you, it is most definitely your script catching and reporting the names list entries. You could search for "raw 353:" in your script to find the code doing this. As sparta said, messing with the code may break the script; it is best to find the line actually printing the names within code, and disable out just that part. Individual script commands can be disabled by prefixing them with a semicolon; this will turn them into comments.
I would take a quick look but it appears that OmegaScript only comes as an installer executable..