app/etc/local.xml

<config>
  <default>
    <enqueue>
      <processors>
        <processor1>
          <topic>topic1</topic>
          <helper>magento-helper-name1</helper>
        </processor1>
        <processor2>
          <topic>topic2</topic>
          <helper>magento-helper-name2</helper>
        </processor2>
      </processors>
    </enqueue>
  </default>
</config>