My terminal emulator is configured for Unicode character encoding and my .vimrc contains the line
set encoding=utf-8
but when I try pasting
How to type a non ASCII code into vi
You'll have to know what your encoding is to enter the proper codes, I assume you left VI at the default.
In VI, go into insert mode, while in insert mode, press
Ctrl-v 172
That should insert the Logical Not (sideways and inverted L) character defined here:
http://www.htmlhelp.com/reference/charset/iso160-191.html