1. sudo apt-get install brother-cups-wrapper-laser
2. Plug the printer into the USB slot. When asked to install a Printer, use the DCP-7020 (no 64-bit driver exists for the DCP-7040) and select the first option for the Brother DCP-7020 foomatic/hl1250 (first option). The ljet4 (third option) will only cause you to print blank pages.
3. Go to http://welcome.solutions.brother.com/bsc/public_s/id/linux/en/index.html and install brscan/brscan2/brscan3 depending on the Brother unit. In this case, brscan3 is what is needed.
4. sudo dpkg -i /tmp/brscan3-0.2.11-4.amd64.deb