how to enter extended characters from Character Map

In Character Map, there are extra characters below the normal 255/256 or
so. I realise many applications can't use them, but some - such as Word
- can.

However, I'd like to know the Alt-key combinations for them. I know I
can copy-and-paste the characters from CharMap itself, but in the case
of ones I use often, it would be convenient not to have to open CharMap
every time.

I have found that in some cases, converting hex. to decimal in
Calculator gets there, but surely there must be a faster way? (For
example, CharMap is currently telling me that the code for "Greek Small
Letter Rho" is "U+03C1"; there is a moderate possibility that if I
convert 3C1 hex into decimal, I'll get the keycode for that character.
Or, sometimes, one next to or near it.)
--
J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf
** http://www.soft255.demon.co.uk/G6JPG-PC/JPGminPC.htm for ludicrously
outdated thoughts on PCs. **

"Forget computers; it's hard enough getting humans to pass the Turing test."
- David Bedno