I made a prx patch that does exactly the same as this tutorial, but now supports M33 NoUMD Mode.
Check it here: viewtopic.php?f=66&t=3280
WARNING: First of all I must say that in order to this patch to work we need to edit a CFWe installed file on flash0. If you do every step as it follows you won't have a problem, though it's very risky. Don't do this if you're not sure about this. USE IT AT YOUR OWN RISK!
Note 1: I'm assuming that you already have IRShell 5.0 installed on your Memory Stick.
Note 2: This patch is only working on CFWE 3.50 version and below. With CFWe 3.60 the PSX games won't work.. (The game could not be started. (800200E5))
Ok, now for the real thing:
1. Download all files from the attachments and unzip them to your desktop.
2. Turn on your PSP, enable chickHen and run the CFWe. Hit SELECT (VSH menu should show up), and change the USB Device to 'Flash 0'.
3. Exit the VSH menu and toogle the USB Connection.
4. On your PC you should see something like this: (You need to have enabled the 'see hidden folders' and have disabled the 'hide system protected files' on your folder options)
5. Open the 'kd' folder, scroll down to the file: 'pspbtjnf_02g.bin' (on ta88v3) or 'pspbtjnf_03g.bin' (on 3k)
6. Copy it to the 'btcnf editor' folder on your desktop (unziped earlier) and run the 'Decrypt pspbtjnf_02g.bat' (for 2k users) or 'Decrypt pspbtjnf_03g.bat' (for 3k users)
7. If done correctly it will create the 'pspbtjnf.txt' file on the same folder
8. Open that 'pspbtjnf.txt' file and find this entry: $/kd/ata.prx VGU
9. Then add this line: $/kd/irspatch.prx VG
It should look exactly like this: (check and double check if it really looks like this)
10. Now save and close the 'pspbtjnf.txt'. Run the 'Encrypt pspbtjnf.bat' file and you should have another file: 'pspbtjnf.txt.new'
11. Delete the 'pspbtjnf_02g.bin' (ta88v3) or 'pspbtjnf_03g.bin' (3k) from the 'btcnf editor' folder and rename the file 'pspbtjnf.txt.new' to 'pspbtjnf_02g.bin' (ta88v3) or 'pspbtjnf_03g.bin' (3k) depending if you are on a TA88v3 or 3000.
12. Now, first copy the 'irspatch.prx' (from attachment) to flash0:\kd
13. And then copy and replace the new 'pspbtjnf_02g.bin' (or 'pspbtjnf_03g.bin') file from 'btcnf editor' folder to flash0:\kd
Again, careful with flash0.. One wrong step and you'll easily brick your PSP..
Now for the easy part.
14. Open the BIN folder on your desktop (unzipped earlier from attachment) and copy all files in it.
Go back to your PSP and cancel the USB Connection. Hit SELECT (VSH menu should show up again) and change the USB Device back to Memory Stick.
15. Toogle the USB Connection again, open 'ms0:\IRSHELL\BIN' and paste&replace all files from the BIN folder on your desktop. In other words: copy 'desktop\BIN' to 'ms0:\IRSHELL\BIN' overwriting all files.
16. Now run IRShell on your PSP and go into the Configurator
17. So you can run ISOS either change the UMD Mode to 'OE NoUMD Mode' or to 'UMD Required'. Note that for 'UMD Required' you need a UMD (doesn't matter which) on your UMD drive. (Makes sense, doesn't it )
18. And change the POP Ver. to 'Use Popsloader Plugin' so you can run PSX games.
19. 'Save Changes & Return to iR Shell'
And it's good to go.
The 2-Player PSX games over adhoc also works. See the tutorial here. (Thanks ruyor for his tutorial)
I tried to make this tutorial as simple as possible so everyone could understand all steps.
If you don't, feel free to ask whatever you want.
PS: Again, use it at your own risk.