For years I've been hoping for OTR to find its way onto mIRC. I decided to put together something that discreetly spawns a local instance of ZNC as a background process, on-demand, through which mIRC piggybacks through it to utilize an OTR module loaded into ZNC. The end result, along with a script I made, feels like a nicely integrated OTR session, and is, at least to me, 'better than nothing'
If you've been interested in using OTR on mIRC, I hope this of use to you. A step-by-step guide is available at http://jollo.org/LNT/doc/irc/otr.html