I haven't tried with Cyrillic, but the Character Map (under Programs > Accessories > System Tools) works for me. It's a bit laborious (you have to find your character, click on it, then click on Select [just because
you've selected it by clicking, you still have to click on Select], click on Copy, and then copy it into your post). For frequently-used characters, look in the bottom right-hand corner of the Character Map window; this gives an <Alt>+ 4 digits (on the mini keypad) version - still laborious, but a bit quicker.
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