XDA Elite Recgonized Developer jcase has posted a method to get the bootloader unlocked, despite HTCDev not supporting it. Also involved in the process is XDA Recognized Developer dsb9938. The method itself doesn’t unlock your bootloader, but it will make your bootloader unlockable.
The method is actually an exploit that allows users to use HTCDev as normal. You’ll need ADB to get it done. Essentially what users will be doing is restoring a modified backup and implanting a generated CIDBLOCK.IMG. This allows your phone to be unlocked via HTCDev the regular way. It is a little complicated, so be sure to follow the instructions to the letter. The method does have the potential to brick your phone if done improperly.
For the full instructions, go to the original thread. For the time being, until jcase can get the instructions put in the thread, you’ll be following the directions jcase wrote on Android Police.