The only possibility that I could think of would be to use a backup program (eg BackupMyPC) that splits an image over mulitple Cds. Installing the game would be a case of restoring the image from backup & mounting the resultant image on a virtual drive (eg Daemon Tools). This is cumbersome to say the least.
I would have thought that 7/8 CDs cost more than a single DVD, but if you've not got a DVD writer then that's not a possible option.
Without constructing a custom install process to request "insert CD 2/3/4" etc I cannot see that there is any easy way.