In the upcoming version of opentaps Open Source ERP + CRM, we have migrated the order, invoice, and quote PDF documents from Apache FOP to JasperReports. This will allow you to modify the layout using iReport:
Instead of editing the xsl:fo XML documents required by Apache FOP:
We have a tutorial on using JasperReports and a tutorial on iReport, although, to be honest, I’ve made quite a few changes to my reports without having to read it.
If you already have XSL:FO documents, we plan to continue supporting those as well.