Add AHCI to MSi S262 bios

Good morning everybody, I Would like to know if its posible add AHCI mod to my amibios 7.08 to use a SSD samsung 850. Now im using it with windows 7 but in IDE mode because in actual BIOS doesnt exist any option to change the sata mode. I´ve unblocked the BIOS and there isnt nothing to activate sata option or so.
the motherborad has i945 GM and ICH7/M southbridge that in theory has AHCI support. Thanks in advance