How to get Request Headers and request content in the handler after it is prepared and before submit

Hi

I am using ReadyAPI and creating a REST request with some header values initially, but once the request is prepared with the inital values I need to interfere the request and need to modify some header values with the request data that gets prepared for submit.

I need the request header information and request content info once it is preapared so that I can modify it before submit.

Can anyone please let me know how can I do it and which handler to use ?

Thanks

Vijay