Or...
Download all of these.
http://exophase.com/files/psp/401.PBP File Details-Recovery-Flasher-v1.50-PSP -
Okay, now put the 4.01.pbp in the root of your memory stick. "G:\4.01.pbp" And then stick the hellcats recovery flasher into your G:\PSP\Game\Recovery\eboot.pbp Now go into your recovery menu and run the PSP\Game\Recovery\Eboot.pbp and the hellcats recovery should come up.
Once your on it, upgrade to 4.01 M33. Make sure you select 4.01 m33 and not offcial firmware.
And after your done with that, check your firmware since you may be on 4.01 m33-2 after. If your on it then you can skip to the 1.5 kernel installation.
--------------------4.01 m33-2 installation
File Details-CFW-4.01-M33-2-update-PSP -
Download that and update your psp to 4.01 m33-2.
------1.5 kernel addon installation
http://exophase.com/files/psp/150k_addon401.rar PSP Firmware 1.50 Download
To install, download the 1.50.pbp and put it in the root of your memory stick (G:\) download the release archive and copy the "150k_installer" folder to "ms0:/PSP/GAME4XX", and run the program through the PSP
-------------------
After all this you should be on 4.01 m33-2. It wont say you have the 1.5 kernel addon, but you do have it after you install it so dont worry. All its for is more homebrew compatibility. Also if you have any questions then just post back.