1. Start Eclipse
2. Help -> Install New Software
3. In the Work With: or Site: input field, enter: "http://download.jboss.org/drools/release/5.5.0.Final/org.drools.updatesite/" and click the "Add" button
4. For the Name you can just enter "Drools"
5. Check the Drools and jBPM checkbox and follow the instructions to get it installed.