The XDA member, Mayazcherquoi has released bootloader unlock tool for Sony Ericsson Xperia X10 that just works in a single click, simply and easily.
Although, the official unlocking tools through official web portals are available there but still if you are not satisfied with those then you must give a try to X10 Bootloader, which could be grabbed through link below.
Official description of work of X10 Bootloader:
What does this do?
This is simply a graphical front end to the_laser’s Windows batch files, with the added questions to prevent accidental device bricking.
Can I use this without having to downgrade to 2.1?
Yes, but make sure you follow 9Lukas5’s guide here. Just disregard the third bullet point and use my program instead
How hard is it to use?
Not hard at all. Just click the big “Unlock Bootloader”* button
What is the point of this?
For people who don’t like black backgrounds and white texts, but feel more comfortable with GUIs
Will you release the source code?
Now? No. In time, yes. Why not now? This is just a quickly developed application and the code is rather embarrassing at the moment
Do you plan to further develop this program?
Indeed I do. I plan to make it a nicer GUI, implement automatic kernel flashing (for those who use 2.3.x), and much more robust. As aforementioned, this is simply a quick mock-up.
Download X10 Bootloader Unlock