Yes but there is more than just the patch_mp.ff inside the .pkg patch file and you can only convert one file to the .pkg format. This means that even if you do use this method multiple files will be missing from the .pkg file and therefore it wont work correctly. In order to make this work correctly you have to use linux to mod the .pkg using some other software that has the power to decrypt and reencrypt the .pkg file. This is because the ps3 was built around linux. But after the recent removal of the other os function it is going to be evn harder to do these types of hacks because we cant have linux on the PS3. But i have been thinking why did Sony remove the other os function within there system. It could be because they found possible ways of enabling homebrew or eable other types of exploits. Other than this all i can suggest is that you get a virtual machine up and running and try modding the patch with ubuntu installed. Also be aware that the patch file (.PKG) is checksummed and will need rechecksumming after you have added CVARS. The more CVARS you add the harder the checksumming. By the way people have been saying that this is not the correct method and Hunter and the Unknown used the decryption of the HDD method. But who knows. These hacks might be achiavable in more than one way.
Good Luck.
1.Unkn0wn doesnt use decryption.
2. There are many ways to bypass the checksums
3. Whats your PSN =D