You must be very special... most of us mere mortals only have
Word 2003, and we'll have to wait about 1,994 years for Word 3000
to come out. The following instructions apply to Word 2003 and
earlier, but I'm not sure if they will work in your version.
Some printers have a "mirror" or "t-shirt transfer" printing
option built into their printer driver... in Word, try clicking
on File | Print | Properties, and see if that option exists for
your printer. If you have Adobe Acrobat (the full version, not
just the free reader), then the Acrobat PDFWriter printer driver
has this option, so you can make a mirror-image PDF file and
print that onto your transfer paper.
If you're trying to mirror text, then see
http://www.gmayor.com/rotate_text.htm or
http://www.word.mvps.org/FAQs/DrwGrphcs/UpsideDownText.htm .
If you're trying to mirror an image (like a photo or a drawing),
then format the image as "float over text" (Word 97) or with a
text wrapping style other than "inline with text" (Word
2000-2003), flip the image using the commands from the Drawing
toolbar, and print.