How to make bootable ISO of Mac OS X Snow Leopard Install DVD on Windows
I read that you can use MacDrive.app (it is free for 5 days).

This is what they say about them self:


  MacDrive gives you complete control of a Mac disk all from your PC. 
  
  You can access Mac disks from your desktop or favorite software, as
  well as create and partition Mac disks. MacDrive even includes robust
  tools to help repair Mac disks that are damaged or unreadable on other
  computers.


The key is it can partition the disk in Mac OS stile, which is must have to make bootable OS disk.

Next step would be to open/extract the OS installer from the OS package (dmg) from your DVD an so on.