I have checked in latest UPD (UPD 10) of APP 10 and it is not possible.
Still it is not allowing to do PR authorization on the total PR amount. It is considering the PR line amount.
This similar concern has been previously reported to RnD and see below for their explanation.
“The authorization for a Purchase Requisition is checked line by line which is clearly mentioned in the help documentation. Therefore this is working as designed. Pls. refer below link. http://docweb.corpnet.ifsworld.com/ifsdoc/Apps8/documentation//en/Procurement/AboutPurchaseAuthorization.htm
Basically authorization validation base on the amount in the PR line, amount can be set to the PR when connect supplier to the PR line. In the PR, the supplier can handle only the line level. Therefore authorization will be performed by comparing the amount of the requisition line with the values entered in the Minimum and Maximum fields in the PR authorization rule. But when come to the PO, the supplier is in the PO header; therefore the authorization for a Purchase Order is checked by the entire order total. When
So, considering above information, the reported issue is qualified as the enhancement request for the future development.”