I personally tried to take the replace the 1.12 default_mp.self by the 1.11's one. Your hacks work, but you can only play on the 1.11 servers ... Which is useless atm.
Anyway, the ONLY difference between 1.12 and 1.11 is the default_mp.self. I backuped every file from the 1.11 before updating ... And I compared the two updates, these are pratically the same, excepted in the default_mp.self.
The EBOOT is the same, no need to mod anything in it.
Otherwise, there is still a possibility to mod the patches, but only for non-host binds atm ... Let's hope people will find out how to get a mod menu working then.