Grishka and I wrote two cross-platform utilities to help with these problems. For inserting single special characters into Mudcat messages, use Grishka's CopyUnicode. For spans of text you copy to your clipboard (as from WP documents or web pages), use my HtmlEsc.java program before pasting. That should be simple enough, even for the tech-averse: Ctl-C (or Cmd-C), double-click, Ctl-V.

The copy-convert-paste approach can also be used for text already in the Mudcat message box, so you can use other composition techniques, like Windows Alt sequences, as long as you remember to convert before submitting previewing.