How to allow users to code at the line level

Summary:

When AP processes the invoice they currently enter a "dummy" distribution set then save the invoice, validate the invoice and wait for the Initiation job to run to route the invoice to the coder/approver. Then Coder will select Edit Distribution, enter the Project/task or GL information and approve the invoice. Therefore, we are not able to leverage the 23D AUTOMATED DISTRIBUTION CREATION USING A TRANSACTION ACCOUNT DEFINITION.

Please advise what we would need to do to allow users to code at the line level so we can leverage the 23D AUTOMATED DISTRIBUTION CREATION USING A TRANSACTION ACCOUNT DEFINITION feature.