Alright, we just got our hands on custom firmware 3.72 HX-2. And now it gets even better, yes its the 1.5 kernel add-on by developer Dark_Moon!

Ok guys, what this little tool does is help us unlock our PSP's even more. For those of you who dont know, a lot of homebrew is made in the 1.5 kernel, now when first installed 3.72 HX-2 DOESNT have that kernel. BUT thats where this comes in, its the kernel add-on!

Ok so here are some notes by Dark_Moon, and also how to install this.

Instructions :

1. When you have installed the firmware 3.71 m33 and the kernel addon download this file and open MS_ROOT. Then copy the PSP folder to the root of your memory stick.
2. Run the app, and press Square. Now the program will start to dump the addon. The dump is on ms0:/psp/game/update/km. Copy the km folder to your hd.
3. Install 3.72 HX. Later copy again the PSP folder that contain this app to the root of your memory stick.
4. Connect the USB (Flash0) and copy the backup done before in the root of the flash0. Run de app again and press X. It will copy the reboot150.prx and all will be done!

So there you go, now guys before you use this be warned that this can be unsafe to try if you are not careful. So read the instructions carefully and enjoy.

Download: 3.72 HX-2 kernel add-on