Cacluating and or Displaying Withholding Tax on AR invoices

Working in R12.1.3 environment.  I have a requriment to generate invoices from US to Mexico.  The invoices will have multiple lines on them and will have withholding tax calculated at one of three rates.  The line and the associated withholding tax line need to be printed and subtotaled on the invoice print.

I know that there is a enhancement request for AR withholding ( and we are going to try to get added to it)

Our current solution would be very manual but it appears to get the accounting right for us.

We will be using memo lines for the service on the invoices and set up memo lines for the withholding tax.