Changing Standard SCDO object

We are having SAP change document object PROJ. This contains the following tables. (View thru SCDO). Now i wanted to add field from AFVC-PRKST into the change document for PROJ.

My final requirement is whenever i change the network primary cost from (CN22) and any other network related transaction it should create a change document under object PROJ and after that i can view this using transaction CN60.

Any info how to change. will be appreciated.

Thanks

aRs