FBXImport -f [filename] -t [take index];
Imports the file specified in [filename] and the take specified in [take index].
The file imported is the one accessible for take querying after the execution of the command.
Specify the appropriate take number to load the corresponding take. If you specify 0, the plug-in imports no animation. (This is the same as if you select No Animation from the menu in the Maya FBX plug-in user interface.)
If you specify -1, the plug-in retrieves the last take in the take array. The plug-in considers any number of takes greater than the amount of takes contained in the file or any negative value less than -1 to be invalid. If this occurs, a No such take error displays.