Heya!!
Try this:
1st: Using A2uploader, upload customize_upgrade.xml file, on this route: tpa/preset/custom
2nd: Discconect from A2uploader, turn your phone on, wait for uploading phone system, then turn ur phone off.
3th: Finally Connect your phone to SEUS program (Sony Ericsson update Service) and you MUST UPDATE your phone (in fact you'll get r1fa030 firmware).
Good Luck!!!