To Install the Xcode Developer Tool Set, you do either of these options.
Option 1: Use your Apple's Install Disc
Go to the the "Optional Installs" folder.
Go to the "Xcode Tools" folder.
Double-click to install XcodeTools.mpkg
If you have a choice to install Unix tools, choose yes (e.g. click the checkbox)
Option 2: Download from Apple
You can download from Apple's software site.
It's a 1 GB download, so it may take a while to get it.