I found loads of guides online with even more text. The problem with these guides is that they explain which button to push but not what it does.
I am fairly tech-savvy which means I try to figure out what is going on and these guides fail to explain that.
So here goes, the TL;DR version to root your HTC Sensation XE and replace the bootloader to make backups or replace the OS.
We start by replacing the bootloader so we can install custom things, including the root access.
- Step 1: Unlock your phone; this is called switching S-ON to S-OFF. I speculate this allows write access to parts of the phone. Follow the HTC instructions here: developer.htc.com
- Step 2: Use ‘juopunutbear’ to unlock and replace the stock bootloader with a version that can be replaced. Yes, the ‘trick’ with the wire is required: it probably triggers a reset of one of the security mechanisms to cheat your way into the bootloader.
Step 3: At this point the bootloader can be replaced. Write your preferred bootloader image from your computer to your phone in the ‘fastboot’ mode using
fastboot flash recovery myrecovery.img; see http://forum.xda-developers.com/showthread.php?t=1864053 and search for the ‘Flash the Recovery’ section which has a link to an image and the exact command for it.
Your HTC Sensation XE now can install custom firmware including the root access. How this can be done is future work.