What keystroke combo is necessary to produce a letter with a macron over it?
(Similar examples: option-U + U = ü; option-N + N = ñ.)

In Lion, if it's a vowel, no sweat: just hold down the vowel key and select the option with the macron over it.

But if I want to put a macron over the letter X (shorthand for "mean"), there is no way that I can find. And there's no such item among the various symbols, technical or math characters.

I've searched the Net and several suggestions have popped up, none of which seem to work for me (Word 2011).

A solution to that problem and the following one would be gratefully received.

I have no idea how to get any UTF-8 symbol into a text even if I know the code number.