Once there open cameras.ini in text editor. Notice the space in between the 1920, 1080. At the bottom it will say and underneath size= change it to 1920, 1080 (or whatever resolution you want to use).Open %USERPROFILE%\ Documents\My Games\Freelancer\PerfOptions.ini.Be sure to restart the game after changing from a 4:3 resolution to a Widescreen. Start the game and select one in the options menu. Your install of Freelancer now supports widescreen resolutions. Add 'jflp.dll' at the bottom of the '' section (under '.\flmaterials.dll') and save.
Do note that some of the servers that are still around use special mods, some of these mods include their own widescreen support. Instead you should go for the INI editing option described further down. If you plan on playing any multiplayer it is recommended that you do not use this option as it might be detected as cheating.
You'll only need to download a file, put it in the right place and make a small edit to another file and you will have the best widescreen support you can get in Freelancer. If you only plan on playing singleplayer Jasons Freelancer patch is a good option.