Hello,
Few years before one of our prospective client was having same kind requiment. He wanted all transactions as cash basis. We found ISV solutions - unfortunetly I didn't remember name of company. They was having solution which was creating another set of GL Account and assigning all entry. So when you create Receivable Entry it was creating Cash basis transaction in another set of GL Account.
You need to contact Microsoft and find ISV provider details.
Thanks
Sandip