So when I read
that mIRC 7 was not going to natively support FiSH encryption, and seeing that the author of the old add-on did not seem to take interest in supporting mIRC 7 so far, I decided to take matters into my own hands.
I'd like to thank for argv0 for taking the time to reply to my post in such detail by the way.
What I came up with is a way that dynamically patches mirc.exe in memory, instead of requiring a static patch for each new mIRC version like the old add-on
You can read more about it here: http://github.com/flakes/mirc_fish_10
(and view the source code if you wish), or go straight to the downloads here: http://github.com/flakes/mirc_fish_10/downloads
You can of course continue to use your old blow.ini configuration files.