I was referring to this method:

How to Install OTA:
1. Download OTA file
2. Rename it 'update.zip' (not update.zip.zip)
3. Put on root of SD card
4. Boot phone into HBOOT
5. Select recovery
6. When at the screen with the ! hold volume up and press power
7. Select 'install update.zip from SD card'
8. Press power to select