Addition of input fields (F4) for Search help in SRM 7.0 - WBS Code

Hi all,

A help required in SRM 7 shopping Cart. My requirement is like i have to add two more custom fields(Engagement partner and Engagement Manager ) in WBS search help pop  up screen and i have to get search result from SRM backend based on the four search criteria.

I want to know which function module or method can make changes and add two more fields.

Please help..