Backup the following files (in your mirc directory):
1) control.ini - the file with the Auto-op, Autovoice, protect and ignore lists
2) mirc.ini - the file with your notify list (and tons of other options)
3) addrbk.ini - file with the Users tab list info
When you reinstal mirc, copy this file to your mirc directory while mirc is NOT running in order to overwrite the file with your OLD settings. This is the same for any of the above mentioned files. I know this is more than you asked for, but I hope it helps.
As a side note, it's been suggested before that mirc use:
1) channels.ini (for thw ALT + J channel list)
2) notify.ini (for the notify list)
in addition to the existing ini files. Personally, I like the idea of that, but they've been suggested before. Just keeping you aware of what has been suggested