Enhancing the Extractor 0FI_AR_4 to get Sales data

we have to extract one or 2 extra fields from Sales related tables in addition to the standard fields provided in 0FI_AR_4 data source.

This note 410799 discribes how to do ?

But I am not confortable with this.

Can we use proceed as we do for LO extractors and write code by enhancing EXIT_SAPLRSAP_001

Regards

Ajay