Just follow the installation instructions in the link I gave above. When you get to the Eclipse site you can choose "Eclipse IDE for Java EE Developers" and on the left select Juno Packages or use this direct link Eclipse Packages | Eclipse Packages
After installation of eclipse you install plugin using installation instructions:
Install the SAP NetWeaver Gateway Productivity Accelerator (GWPA, Developer Edition) feature(s) .
From the Eclipse menu, choose Help> Install New Software...
Add the URL:https://tools.hana.ondemand.com/juno
Select the feature(s) you want to install and follow the steps of the installation wizard.
For information about the individual features, see the documentation.