Have a look for the cheap socket sets usually in the £1 shops in most I have seen they have a hex to 1/4 square socket that you could then fit to a socket to fit the tap. Not sure a tap that small will be 1/4, I thought they were a bit smaller. Not sure if the setup will be in line enough to tap square though.
Have you tried tapping the thread holding the material in a vice to try and stop it splitting.

Peter