Hey folks KaKaRoTo, famous for his work on the PL3 payload, has released a tool that converts a standard Sony retail firmware files, into a Custom Firmware. The custom firmware allows the installation of homebrew files (via package install), without the need for a jailbreak.
Please note, this does not appear to have the necessary patches in place, that are necessary for playing backups. However, that is a very trivial matter, considering the grand spectrum of what KaKaRoTo has achieved.
Read Here on how to apply this Custom Firmware