"Are you sure you wish to continue? You are about to start the process of unlocking your device. Unlocking your device allows you to install custom Operating Systems (“OS”) onto your device."
Words many have been waiting to hear, and starting today, owners of the European version of the HTC Sensation can now put them to task -- HTC's bootloader unlock page has went live. You'll have to accept all the legal terms and agree to them, specifically that your warranty may be void (in full or partially) and that HTC may charge for warranty repair work on unlocked devices. We've known about this, so you shouldn't be too surprised.
You'll then be walked through the entire process from start to finish. The instructions are extremely well done (they would be worthy of a sticky in our forums) and explain exactly how to use the needed components of the SDK with pictures, download links, and all the commands listed -- it's all a copy and paste job. You'll be instructed to get a unique device "Identifier Token", which you'll submit to the HTC bootloader page. They will in turn send you an email (to the address you registered on the HTC developer site with) with an unlock key and needed commands to use it. Then you're gold. It's all pretty well documented and the commands seem simple enough, but remember -- there's never much room for error when doing this kind of operation. Make sure you understand the process completely before you begin.
And that's it. A simple solution to a problem that a lot of us have had with HTC. Now we wait to see it be released for devices here in the states.
Source: HTC Dev. Thanks, Kevin!