No, it needs to be a DVD - you can use most DVD drives from PCs in the G4 if it's still got the stock CD-only drive, it doesn't need to be a Mac-specific one. You can strip down the Leopard DVD to fit onto a single-layer DVD if you don't have any dual-layer discs.
It'd be a bit of a waste to turn it into an aquarium, those dual processors are fantastic!
It'd be a bit of a waste to turn it into an aquarium, those dual processors are fantastic!