Thanks for the suggestions. I know how to connect to tor, I can even use tor from command line I suppose, so technically it might be possible for me to script miranda to start tor when miranda starts (maybe?). My point was, I wanted to have a portable miranda (which it is, by default) with the ability to make all of its traffic go through tor (which should be portable as well). Vidalia needs to be installed. AdvancedOR does not but I don't have any experience with it. I think I'll just make a script that starts tor or something.
A plugin would be nice - but I agree that it's perhaps a bit too niche.