if anyone know please help me
You shouldn't wonder no one has responded to your question yet.
Firstly if you expect to modify slightly the ant script and - jbpm4.2 will be installed easily on WAS 7 - that is not so easily and quickly done.
As it is, jbpm is not really dependant on any app server. You can use it as a library in your project deployed on almost any app server.
What you probably want is to install the jbpm console.
Well this is not possible by modifying just the ant script, at least not possible without some modifications in the project and probably having to rebuild from source.
There is neither a tutorial for this nor is this supported by the jBPM team.
I have seen the console running on WAS6.1, but as I said the guy who managed to install it had to modify the projects and build from source.
Since that was for his company, he will not be able to provide any tutorials here. You have to try it yourself.