While Sony Ericsson may not have released the dual touch update outside of Japan yet, the folks over at XDA have once again, been hard at work. The recently released dual touch update can now be applied to any Xperia X10 handset. You will need the latest version of flashtool and the Dual Touch FTF file available from here.
Once downloaded, you will need to extract and install Flashtool if you haven’t already and put the dual touch FTF file in the “firmware” folder of Flashtool. You will then need to hit “Flash” on flashtool and it will tell you to connect your phone in flashmode before selecting ok. You can put your phone in flash mode by turning the handset off. Once off you will need to hold the back button while plugging the USB cable in and hit the OK button promptly. You’ll then need to select the firmware you want to flash to the phone, in this case you’d select the dual touch FTF file.
Unfortunately to get full use out of it, you will need to also root your handset, which you can also do with Flashtool. After rooting, you will need to install Root Explorer and follow these instructions here. I personally skipped stepped 1 and proceeded with step 2 and can confirm that just doing step 2, will work. Without doing this, the dual touch update only works within third party apps and not the browser or Google Maps.