I just had the same problem but fixed it!
First you need all the files (M2T, IDX and DAT)
Make the folder-structure like this:
Put the files in a folder called: “HVR”, then put the “HVR”-folder in a new folder called “video”. Make shure the Folder called “video” is not in any other folder. Ploblem salved on my fcp 7 but i think its´the same on fcp 6