Is it using the restore disc provided with the iBook or with the original Tiger Disc ?

either way , its the same. You just pop in the OSX Installation Disc or Restore Disc and then hit C. It should boot from the CD-ROM/DVD-ROM...Then OSX Installer Wizard would guide you , just format the HDD [Dont select Archive and Install , unless you wish to backup his files and just install a clean copy of OSX'...Its pretty easy to install as the installer guides you