Ok, so once in bootloader mode, you want to select fastboot (it may be the initial setting once booted into bootloader. You'll know if you see fastboot on the screen). Once there, download the fastboot file for your OS (from here on out, I'm going to assume you're on Windows) from the psfmod page (
http://psfmod.klutsh.com/tools/fastboot-win.zip) and extract it into a folder. Let's say c:\fastboot just for arguements sake. Now that you have the files in c:\fastboot, download the recovery image (
http://psfmod.klutsh.com/recv/psfMod...ic-0.9.7.2.img) into c:\fastboot. You should now have the 4 files from the .zip and the .img file all in c:\fastboot. Now, you'll want to open a command prompt window and navigate to that folder (cd c:\fastboot). Once in the folder, connect your phone to your computer (still in fastboot in the bootloader) and type:
fastboot flash recovery psfMod-supersonic-0.9.7.2.img
You'll see some information go across your computer screen of it loading the recovery image. Once it's done (it's always best to wait a full minute after the flash just to make sure everything is done), select reboot phone on your screen. Once it reboots, you can now boot into recovery and you'll have the psfmod choices in there.