actual work & duration in confirmation screen IW41/IW42

Hi al,

My requirement is to capture manpower cost as well as duration of work performed.As we enter work & no of person field in operation tab page of IW31 screen, duration gets calculated automatically .Same way my users wants to enter any one of the following three fields in IW41screen ---(a) Actual work or (b) Actual duration or (c) work starts date,time & work ends date,time.

and other two fields should get calculated automatically.What I need to do to make it happen meeting my requirements to calculate the manpower cost & duration of work performed as in IW41 screen there is no field called no of person?

Thanks in advance.

rgds

rajib