After encountering pretty much the same problems and working through them myself, I thought I'd chip in with a bit of assistance for anyone else who's been stuck at this point.
First of all, when unzipping the Android SDK you download from the link, you don't go to the eclipse folder. Depending on your unzip program and location, you want to tell the command prompt to go to the folder adt-bundle-windows-x86-20130917/sdk/platform-tools.
Second, at least on 64-bit Windows 7, the instructions are slightly incorrect. Instead of putting $ fastboot oem get_unlock_data into the command bar, it's actually fastboot oem get_unlock_data with no $ or space at the start of the command line. My key is different to deltalinxx's, so each phone probably has a unique one and I wouldn't recommend using someone else's.
Next, as the instructions admittedly say, when you click on 'Request Unlock Code' at the bottom of the page, you don't get it on the page - it's emailed to the Google or Motorola email account that you used to access the instructions page in the first place. I found that I actually had to block a pop-up on the page to get it to work - if you get a completely white page, it hasn't.
Once you have the code from your email, again, you skip the $ and space at the start of the given commands, so it's just fastboot devices and fastboot oem unlock UNIQUE_KEY .
Edited by Tarrn, 14 January 2014 - 12:29 PM.