User Exit for IW41

Dear All,

I have one requirment in which I have to create one pop-up screen after the initial screen of transaction IW41.In that pop-up screen I have to create one cost center field .When I will enter this field and press enter then it will go to next screen.

and this this cost center will update in respective structure.

I have find out one userexit for that CONFPM01.

Could you tell me is it ok and possible or do you have another method?

Regards,

Amar