Keep your .tga files in one folder, and it is important that the file names be sequential, and to have the same mumber of digit spaces to increment all across the name, for example: "subject0000.tga", "subject0001.tga", etc. This keeps individual frames from getting put in the wrong order later.
I go to my FCP user prefernces, and set the default duration of imported stills to one frame. Then I create a new bin in the project, drag the folder of .tga's into that bin, do a select> all, drag that to my timeline, done. From there I can also render out a self-contained .mov file if needed.
I'm told you can also use a function in quicktime pro for exporting image sequences as .mov files.