This requires the installation of Python and pyPDF. Out of the gate, the script does not provide for image overlap, however there is a patch that does fix this. The patch requires replacing 5-6 lines in 3 files and adding 2-3 new ones, its very easy.
This very simple script requires the installation of Python, Python imaging and ImageMagick. Its crying out for a web front end and maybe generalization Perl and PHP versions as well as a front end. Nevertheless I tested it out and it does work.
Use the Poster program to create a Poster from an EPS or PostScript file. This is the grand-daddy of all poster programs and still exists as a Linux package. It was written in by Jos van Eijndhoven in 1995. Pdfposter depends on it. it only works with ps and eps files.