Well it was pretty easy. For anyone interested, here is exactly what I did.
1) Download the latest version of Kindle Fire Utility (also worth mentioning, my software version was 6.3.1 on the KF)
2) Make sure your Kindle Fire is unplugged. Extract the zip file and run the driver installation bin file.
3) Plug in your Kindle Fire. Go into Windows Device Manager and check your driver. It should say android phone--> android composite adb interface or something like that....definitely the word composite. If it doesn't, you need to update the driver. Point it to the KFU directory and it should find it.
4) Boot up KFU. It should show that adb access is online.
5) Run the command to install TWRP. It will boot into fastboot, do its thing and reboot back into the system. Then download the FireFireFire bootloader from the thread on XDA and put it on your sd card.
6) From KFU, change your bootmode to "recovery" and reboot the device.
7) Flash the bootloader in recovery, reboot into the system.
You're done. You'll have a custom bootloader and recovery. Technically you'll be on an unrooted stock rom, but it will be similar to being S-OFF on the Evo without having flashed superuser. Which is fine with me, because I don't want to be on the stock software anyway. Flashed Glazed ICS (a CM9 build) and it's freakin sweet.
Obviously your mileage may vary, but that's what I did and it worked like a charm.