Flipping text in a \markup

[Sven Axelsson]

I am using Lilypond for classical bagpipe music (piobaireachd). To write this
correctly I need a markup consisting of a a single letter rotated 180 degrees
around it's center (i.e. put upside down). This can be done using \postscript
markup, but I don't know how myself. Can anyone give me a hand? The letter
should use the current font and size for text markup.

Thanks a lot

-- 
Sven Axelsson