Hello,
This works for me:(v5.4)
-Download and install jbpm-5.4.0-Final-instsller-full.zip
-Now you have org.drools.updatesite-*.zip in your jbpm-installer/lib folder
-In Eclipse, point Help-Install new software ... , press Add... then press Local...
-Select that updatesite zip
Note that this will install jBPM5Eclipse plugin, which is said to be obsolete(see docs for details)
hope this will help