Ensure you have Java 1.5 Release 4 installed or later. This is freely available for OSX 10.4 (Tiger) but may not be installed by default and is not part of the automatic Apple Updater , it is available at http://developer.apple.com/java/download. Ensure you get the correct release for your Mac (Intel/PPC).

Download the Jaikoz.dmg.zip from the Website

This should automatically mount itself as an additional drive.

Copy Jaikoz to your /Applications folder

Start Jaikoz, if you have not installed Java 1.5, the following dialog will be displayed, in which case install java as required and retry