It was done by Jerpelea, biktor_gj and Bin4ry!
This is Idiot proof in 4 steps (thanks Jerpelea for that )
First download this file and extract it:
Now please read the HowTo.txt and find your DeviceID in registry and edit the DeviceID.txt in step1 and step3 folders!
Now run step1.bat. This flashes your phone to R1EA018 S0-O1B firmware
After flash is done, take battery out wait 5 seconds and put it back in after that boot the phone again!
When phone is running again activate USB-Debugging.
Then run step2.bat. A Menu should popup
Choose option 6!
The phone reboots and flashes. After a while is it done.
Now run step3.bat. This will flash new R2 Baseband for X10i (this is for X10i only!)
After this is done. The phone reboots.
Now run step4.bat. This will get you root, and delete SE and Docomo Stuff from phone. It also installs some small apps which are useful
After all steps are done you have now rootshell at your phone
(Your phone says now it's S0-O1B but this doesn't matter! It's only the Software which says it is, don't worry it's same phone )
Your Firmware and Baseband Version shows in Menu like "old" Version (Firm R1EA025)
BUT this is because its hardcoded in bootimage. If you flashed "new" Versions in step 3 you get the new Baseband, the phone only doesn't tell you )
So this is easy and first root for X10!