Reply to the whole thread, not to Raccoon...
I'm running four clients on three networks with three of the clients connecting to multiple networks, with only a single installed copy of mIRC on a Windows 7 x64 box. All four clients have separate alias and remote lists. The only thing I needed to do was create separate shortcuts with different -r parameters. mIRC is installed in Program Files (x86), and the folders/files for each -r are in a separate directory subordinate to My Documents. No messing with the registry, no installing as portable, no digging around in %appdata%, just straight up.
