How to access BIRT 2.3.1 using JDK 1.4

Hello,
I am facing issues while deploying code in WAS 5.1 ussing BIRT 2.3.1 as the JDK used in WAS 5.1 is 1.4 and requirement for BIRT is JDK 1.5.
Can anyone suggest me the alternative to this as my application is not compatible with JDK 1.5.
Is there any interface available??