Would it be possible to specify a particular Unicode character (or a character from another character set) rather than attempt to enter the literal character?
I am using PM under Win XP, so to enter the copyright symbol (ISO-8859-1 character 0169) I can hold down the ALT key and enter "0169" on the numeric keypad. However, that requires a lookup of the code for a specific character, and might not work well on systems using other default character sets.
I thought I would be able to use Code Replacements to simplify the use of some common characters. I setup "c" as a code for "©", "tm" as a code for "™", etc. Unfortunately, this does not work well. When I tested it I found that entering "\c\" in an IPTC field resulted in a "?" character. As I should have expected, code replacements does not seem to handle such characters. The IPTC field, however, does handle these if they are directly entered.
Perhaps you could add a special variable such as "char" which when used as {char:169} would insert character 169. A similar "unicode" variable would be a good idea; the same copyright symbol code thus be inserted with {unicode:00A9} (assuming you wanted it in 4-digit hex).
-Ian