Copy away and save this file:
%ProgramFiles%\mIRC\mirc.ini
Keep that file on your CD somewhere, and restore it to the right folder after mIRC install, using batch-files or something.
Or, even better:
1. Install mIRC 6.16
2. Configure it to how you want.
3. Copy away "%ProgramFiles%\mIRC" to somewhere.
4. Put that folder now on your CD "$OEM$\$Progs\mIRC"
5. And the shortcut to it - "$OEM$\$Docs\All Users\Start Menu\Programs\mIRC.lnk"
That's it.