Brother printer: how to build driver with no instructions at all?

[endocub]

SOLUTION: I installed brscan4, did

$ sudo brsaneconfig4  -a  name=SCANNER  model=MFC-J491DW  ip=<printer's id>
$ brsaneconfig4 -q | grep SCANNER
* MFC-J491DW   [  192.168.2.221]  SCANNER

and now my Brother scans like a firie!