Flash 900Sm to become a Back Haul??

is it possible to flash or modify firmware of a 900SM to be able to act as a Back haul or an AP?
we have a lot of Sm and we would like to connect a few like an Ad Hoc network or point to point.
I think it is only software related , the hardware is pretty much the same??

No, you are unable to flash or modify an SM to act as a BH or AP.