My daughter bought a cheap Windows PC a couple of years back to play the online game Final Fantasy XI. The company recently released a game expansion, but the software is on a DVD and her computer does not have a DVD drive. After trying to share the DVD drive from another PC and failing, we gave up on a pure Windows solution.
So we put the DVD in my Mac laptop's drive, and after it mounted, I opened Terminal and created a Unix link in my public directory to the DVD.
cd ~/Public
ln -s /Volumes/FFXI
Once her PC located the shared drive on my Mac, she could install the software as if the DVD drive was part of her computer.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060420105632844