mIRC does support characters beyond the BMP through UTF-16 surrogate pairs - it is just $chr/$asc that don't. $chr/$asc equivalents
can be scripted although it would be nice if this functionality were built in.
Unfortunately it seems not to work for me. I tried jaytea's UTF-16 demonstrations, and mIRC displayed the constituent surrogate pair (as two characters) instead of a single character. I'm guessing that it's a Wine (1.0.1) issue.
