I wrote this for a forum post, and figured I would share it here too. Hope it helps. Check the XDA Developers forum and http://www.cyanogenmod.com/ for a lot more info. None of these files/roms were written by me, and all credit goes to the people who did the hard work. As usual, I assume no responsibility. Unlocking your bootloader will technically void your warranty. I’m just telling you what worked for me, I’m not a professional. I wouldn’t even listen to me, I’m usually drunk. There’s a solid chance I’m just making all of this up. Also, I did this all on a Mac running OSX Snow Leopard. If Linux/Windows/Whatever is vastly different, you’re boned, and it’s not my fault. Essentially: Don’t come crying to me.
Download the Android SDK:
http://developer.android.com/sdk/index.html
This will get you a .zip file. I would extract it to the root of a drive or just one folder down (like to C:/ or ~/ in mac or C:/sdk) You’ll understand why later. After it’s extracted, go find the “tools” folder. Double click the “Android” file. It will pop up a command/terminal window, then a GUI. In the GUI, click on “Available Packages”, select all of them and install. This will take a bit. When it’s done, you can just close the window and the command prompt.
Now you need to add fastboot. You can compile it yourself, but that would be silly. Here’s a windows 32 bit version I found on XDA:
http://files.me.com/mzsigler/v94lxh
Extract the zip to the “tools” folder in the android SDK.
Here’s the Mac version, it’s not compressed, just download it and put it in the “tools” folder of SDK, no need to unzip.
http://files.me.com/mzsigler/29kua4
In all honesty, I don’t remember where I downloaded that file, but it works great. If you compiled it, please let me know and I’ll credit you.
Then you need Amon’s recovery image. Save it in the “tools” folder in your SDK (picking up on a pattern here?).
http://rapidshare.com/files/366400383/recovery-RA-nexus-v1.7.0.img
Then you need a new rom. Download it to your computer, then move it to the SD card on your phone, don’t unzip it or anything. I highly suggest this one from CyanogenMod. His roms are fast and stable, by far the best I’ve found.
http://n0rp.chemlab.org/android/nexus/update-cm-5.0.6-N1-signed.zip
I believe in windows you need to download some drivers, but I’m not sure, as OS X didn’t require any drivers. Windows users should google “Android USB drivers” right about now, and come back when they’ve made sure they have the right ones.
Connect your phone via usb and put it in bootloader mode by turning it off, then holding the trackball down while you power it back on. It should boot a white screen and say “Fastboot USB” near the top.

On your computer, open Command Prompt or Terminal, depending on your OS, and navigate to the folder the SDK is in and find the “tools” folder. If you listened to me and saved it somewhere easy, like the root of a drive, this is simple. Say you saved it in C:/sdk. You would click the start button, then “run”, then “cmd”. This gives you a command prompt. To get to the proper folder, you would type “cd\” to go to the root of C:, just so we’re all on the same page, then “cd sdk/*android_sdk_orwhatevertheynamedit*/tools”. In my case, on a mac, it’s “cd /android/android-sdk-mac_86/tools” If that still doesn’t make it clear, you might be better off just leaving your phone on the stock rom. Effectively, navigate to the tools folder of the sdk in terminal/command.
Now type “fastboot devices” and hit the enter key (Or “./fastboot-mac devices” for a mac) and see if it recognizes that your phone is connected If so, you’re ready to go.
*When you unlock the bootloader in the next step, it will wipe the phone and erase all of your data. Any pics on the SD card are safe, and you can redownload the apps you’ve paid for, but if you have a text or something you find important, make sure it’s backed up*
First unlock the bootloader. Type “fastboot oem unlock” then hit enter (Mac: “./fastboot-mac oem unlock”). It should walk you through the unlock process and warn you that your warranty will be void. Just follow the instructions. Once you’re done, boot back into bootloader mode by holding trackball and powering up. You should have an open lock under the multicolored Nexus X now.

It will take you back through setup, but you can just power down, since you’ll have to setup again when you flash the new rom.
Now you’re gonna flash the recovery image. Again, hold the trackball while you boot the phone to put it in bootloader mode, and again, in command prompt, navigate to the /tools folder and type “fastboot flash recovery recovery-RA-nexus-v1.7.0.img” (Mac: “./fastboot-mac flash recovery recovery-RA-nexus-v1.7.0.img”)
It should flash the recovery image. Now reboot into bootloader again. (Hold the trackball while you power your phone on) This time use the volume and top (screen lock) button to navigate. Press the top button to select “bootloader”.

It will load another screen. Press the volume down button to select “recovery”. At first it will do nothing, this is normal, it’s checking the device. You’ll see a few things flash on the screen in green, again, normal.

It will go back to the menu, and now you can use volume down to select “recovery”.

Highlight it and press the top button to select it. You’ll see the multicolored X as it boots into recovery. At this point, your trackball will be used to select things.
Go to “Wipe” and do a “Factory Reset” wipe first, then go back to the main menu.
Select “Flash zip from sd card”, pick the file I had you download above (the rom file), confirm that you want to flash.

Once it finishes you’re done. Boot up and set up your phone.
Email mobilesig@gmail.com if you spot any mistakes.