Hi there,

I have just finished writing my tutorial on upgrading to the latest 3.71M33 firmware, and it is available here:
PSP Custom Firmware 3.71 M33 Guide | Karol Krizka

It includes the following:
  • Step By Step Instructions
  • All Needed files
  • Instructions for 3.71 M33 Upgrade
  • Instructions for adding 1.50 kernel support
  • Instructions for installing the Custom Firmware Extender 1.6