Header Value from JMS message

Hi Experts,

My Scenario is JMS to JMS.

Here we have a requirement to get the Header values (not standard header fields) from JMS Message and populate it into same field in receiver JMS channel.

If these are standard header fields in JMS ,we could have used ASMA and get it into PI message header.

But in my scenario this  header values which we need to read are present under user defined (usr) tag in header.

Can anyone let me know how to achieve this ?

Thanks,

Manohar