Well here's a little gotcha (from perldoc perlunicode):

Unicode characters can also be added to a string by using the \x{...} notation. The Unicode code for the desired character, in hexadecimal, should be placed in the braces. For instance, a smiley face is \x{263A}.This encoding scheme only works for characters with a code of 0x100 or above.

You could say $x = pack("U", 0xfc);