In jBPM5, use a rule task and give your set of rules a name (i.e. ruleflow groupattribute).
Next, use Drools to define your rules and add these rules to the group you selected (using ruleflow-group attribute).
Your rules should now be executed when you reach that node.
Example can be found here:
I am using jbpm 3.2.3. So sorry i forgot to mention that before.