PDF rewriter: concatinate/merge pdfs

I read this well written article: http://cqblueprints.com/xwiki/bin/view/CQ+FAQ/How+can+I+configure+the+ PDF+rewriter

and was able to edit the file here: /libs/wcm/core/content/pdf/page2fo.xsl  to convert my .html file to .pdf on the fly.  But I have front and back cover pages which were created in InDesign and saved as .pdf files. I need to do this:

front.pdf + <myFileReWrite>.pdf + back.pdf    =>   <myFileReWrite>.pdf

front.pdf and back.pdf are uploaded to my digital asset and currently sit at: 

   /content/dam/<someFolder>/front.pdf

   /content/dam/<someFolder>/back.pdf

Is there a way in CQ to merge these pdf files on the fly? 

Thanks.