If the as command is not found (powerpc assembler) then I doubt Xcode tools are installed. Check by using the finder and going to [MacintoshHD]->Developer->Applications.
If it isn't use the finder to go to [Applications]->Installers->XCode Tools and run the installer.
If that isn't there put the OS DVD that came with your Mac or the separate XCode Developer Tools CD in the slot and install from disk.
If it isn't use the finder to go to [Applications]->Installers->XCode Tools and run the installer.
If that isn't there put the OS DVD that came with your Mac or the separate XCode Developer Tools CD in the slot and install from disk.