If you have already successfully installed Amon Ra, skip to 1. below. If not, you write the Amon Ra recovery to the bootloader by opening a command prompt on your PC, navigating to the directory where you put adb and fastboot from the SDK. You should have also put the Amon Ra image there. I simply copied mine there and renamed it to image.img. Your phone must be booted to fastboot and connected to the computer with settings as in the OP. After all of that is true, type the command "fastboot flash recovery image.img" ( without the quotes, in my case I typed for the recovery image "image.img", because that's what I re-named it)
1. After successfully pushing the Amon Ra recovery to the phone, power down.
2. Take the battery out and replace it.
3. Reboot by holding down the volume down and power keys until the phone reboots into fastboot.
4. Use the volume keys to select recovery and then press the power key.
5. From the recovery menu use the volume keys to select advanced and then press the power key.
6. From the advanced menu use the volume keys to select install superuser and press the power key and let the phone do its thing.
7. Power down, reboot and you will be rooted.
I hope this helps...