Data reconciliation for Open Orders

Hi,

Can any one give me the step by step approach for data reconciliation for open orders in Sales Infocube. I understand that the Open Orders which are dynamic Key figures and the data reconciliation in this case is not straight forward using "Generic View data sources" and we need to program our own generic data source with a funciton module. I would like to know if any one has dealt with this specific case and give me the proceudure to do the same.

Regds

tanu