I could not import a range into FCPX due to moving the original clips onto a separate hard disk which made them a .mov file. I could import the entire clip but not a portion of the clip.
What I discovered was, if you copied the camera card onto your hard drive ( in my case the Canon EOS_DIGITAL ) you would then have a folder structure EOS_DIGITAL/DCIM/MISC.
Delete the MISC folder first; then inside the DCIM folder there are 2 folders 100CANON and EOSMISC. Inside the 100CANON folder are your original clips, both still and movie. Create a NEW FOLDER on your hard drive and move your still shots ( photos ) into your new folder, rename it however you wish. Create another NEW FOLDER on your hard drive and move your .MOV files into that, again rename it however you wish. DO NOT change/rename the location of the EOSMISC folder ( this has a .CTG file inside which I assume is a DB file )
OK, you now have a new camera card folder; EOS_CANON/DCIM/100CANON/EOSMISC. Keep this as your MASTER. Make a new copy of this folder. You can rename the EOS_CANON to whatever ( I use NEW CARD ) next rename the 100CANON also as you wish ( I use footage ) DO NOT CHANGE the DCIM folder.
You can now move any .MOV files into the footage folder and you will be able to import selected portions of each clip ( range selection ) in the import window of FCPX.
So far I have been able to apply this from both Canon & Sony footage as well as iPhone and old Hi8 files as long as they are in the .MOV file format. This was done using a Canon Card and I have also used a Sony Card, although this is done with a different file structure. This also works with MP4 using Sony XACVS file format. I only discovered this yesterday so I haven't really tested if there is any degradation in the clips but from just viewing, there seem to be no loss.
Sometimes when you have the import window open ( usually when you click open the new clip folder for the 1st time ) you will see the file structure NEW CARD/DCIM/Footage. The clip inside the folder Footage will show the old .mov file that is only importable NOT range selectable. If this happens just collapse the NEW CARD folder and re-expand this folder, you will no longer see the file structure only the clips you have placed in the footage folder. These are now range selectable.
If you don't want to mess around creating the structure manually, theres an app called VirtualCameraCard that creates a sparse disk image set up for just that purpose. It's available from http://www.spherico.com/filmtools/