Internet Sales Development and Modifications

Hi,

I was reading the Internet Sales Development and Extension guide and it was mentioned that SAP does not release Java source codes for ISA.

Has anyone any experience in modifying ISA and how much can be made without source code ?

A prospective client would like the ISA to be modified to suit it's business requirements (i.e additional fields, drop down selections and buttons).

with our limited knowledge we do not see how this can be done without source codes.

Anyone has any ideas to share ? Any inputs and ideas would be greatly appreciated.

With regards