See the post at http://blog.ibd.com/scalable-deployment/getting-the-jet3t-s3-gui-tool-to...

Jets3t (pronounced "jet-set") is a free, open-source Java toolkit and application suite for the Amazon Simple Storage Service (Amazon S3) and Amazon CloudFront content delivery network. For some reason almost all the standard tools for accessing S3 will not easily work with the Eucalyptus equivalent to S3 called Walrus. I am use to using the excellent S3Fox add-on for Firefox and wanted some GUI tool that had similar capabilities. I was able to piece together how to get Jets3t to work with Eucalyptus Walrus. This article puts it all together in one place.

The basic build procedure is based on the instructions for downloading and building Jet3t from Source. I got the hints for what to change to make things work with Walrus from the Jets3t Users Forum article eucalyptus walrus. And an almost unrelated article hadoop in eucalyptus private cloud in the Cloudera Support Forum. Search on the page for the section that says my jets3t file has these values.
These instructions assume you are on Ubuntu (I had 10.4 Lucid) though it should be easily modifiable to work on any platform that supports Java.