JMS load balancing technique

I have a JMS server running on a clustered environment. It accepts a request and  puts into a queue. The requests from the queue are then send  to one of the nodes for processing. The problem is when one request is heavy and the one just following is light. The heavy request takes a long time to process and the light request is forced to wait until the former is done. Is it possible in IBM Websphere 6 to send the request to different servers two at a time(or maybe more) so that a single request does not hijack all the resources? If yes, do we need a configuration change or we need to write a custom component for that?