placing multi-page PDF into existing image boxes

I've created a multi-image box page in InDesign using the step & repeat feature. Now I need to place a page from a customer supplied multiple page PDF within each box. I have one to do now that has 100 pages in the PDF - how can I automate placing the pages within the boxes I've created? I read about a grid feaure that can be worked to do something similar, but I need to add a "CutContour" line around each box so the printer can cut it out once printed, so I'm unsure if this would work.

I could create one InDesign page per PDF and import automatically uing the multipageimport script, but then I'd have to create a print PDF (need to do this so I can add the cut shape info to each page), split it into 100 PDFs and have the production dept bring each page into the RIP separately - I'd prefer to give them one large PDF with all 100 pages in.

Hope that makes sense! Thanks in advance.