I once spent a little time with CAM::PDF (after reading the same sources you did). I intended to use it for form field replacement (as you are). My experience was that the documentation and examples didn't quite match the layout that was coming from my PDF form source. At the time I was using open source PDF editors to create the forms and there were problems just generating a valid form to start with (form fields were just too advanced and buggy for the edit tool). In the end, I gave up on using forms, and simply created my PDFs from scratch with PDF::ReportWriter, eventually contributing more formatting features which can be found on Daniel's website http://entropy.homelinux.org/axis/PDF-ReportWriter/.

My failure make CAM::PDF work was due to invalid PDF form sources. With valid form sources, I'm sure it will work fine, but maybe not exactly the way the examples show it. This probably doesn't help you much, but I hated to see the question go unanswered.