AR Receivables Conversion

as part of a conversion We are in the process of beginning a PS AR conversion and would like to know if there is any documentation available on helping with the following.  We are coverting from a highly customized home grown system which has the following information:

Invoices (items)

Item balance details such as CR memo's, DR memos, payments, CR / DR offset transactions.  Some of these items are open, other are closed

The Customer information has been moved to PS CRM.  We have a feed from PS CRM to Peoplesoft AR which based on triggers in PS CRM create the necessary items in