Review:
I don't use PsyBNC, so am unable to test it there. This snippet works by checking for an inbound server message where the 2nd token is 005. Any tokens which are exactly those 4 words are stripped from the line, and the edited line is sent for mIRC to 'see'. If mIRC can't see these tokens in the 005 message, then it shouldn't change its behavior in response to these network settings.
You should be able to paste this snippet into any other existing script, as long as you place it on a line above any other PARSELINE event handlers.
It might be possible to selectively apply this per network, depending on whether you can reliably test $network or the server name at this stage of connection.