This repository has a build script and the required files to build an OpenWRT firmware compatible with Movistar FTTH (for Spain). With this firmware you can change the provider router and use a TP-Link TL-WR1043ND or Linksys WRT160NL.
First of all you need a Linux distribution with development packages. For example, in a Debian based distribution you can ejecute:
apt-get install git build-essential subversion wget python unzip gawk libncurses5-dev zlib1g-dev
Then you will have to execute the build-firmware.sh:
sh build-firmware.sh
This will clone the OpenWRT repository and apply some changes. The config is set for TP-Link WR1043ND, if you want to build for Linksys WRT160NL you will have to change the target platform using the comand make menuconfig before make -j8.
Once the build has complete, you will find the new firmware in the bin/ar71xx/ directory.