FBXImportSetLockedAttribute -v [true|false]
This command is the scripting equivalent of the UI dialog box Keep all locked or unlock all options. Use this command when you import an FBX file that contains animation onto an object that has locked channels.
When you use the UI, the Maya FBX Plug-in prompts you to either keep all the channels locked or unlock the locked channels, which imports the animation correctly. This had created problems for users who tried to do this without working in the UI.