That is the correct firmware file and your device already has it installed. You need to install the CSSU next and then the diablo turbo kernel. After that I suggest installing a bootmenu and cloning. Only use the cloned installation, so you can boot into the untouched primary installation and recover the cloned installation after it crashes and won't boot. http://maemo.qzx.com/ - that has links to do the above and more.