Are you saying that your CD Rewriter is the Master on your Primary IDE channel, and the DVD is the Master on the Secondary channel? "master slave" doesn't make any sense...
Anyway, I'd guess that the installer is looking in /cdrom for the CD. You could become root and change the symlinks so that /cdrom points to the DVD drive, then change it back later, but that sounds like a fair bit of hassle. It's more likely that you can tell then program which drive to use somehow. Put the disc in your DVD drive, then look for an option that allows you to specify the location of the install files. If you really can't find it, then playing around with symlinks would work, but it will require you to be root.