I backed up/copied Canon XF300 footage from CF card to external drive for later use. I now need to import the material into my FCP project. Normal Log and Transfer doesn't recognise the files. (I do have the Canon plug in installed) I get a warning...."MXF contains unsupported media or invalid directory structure"
How can I import the MXF footage?

If it's like most MXF camera's you need to copy the entire directory structure for log and transfer to find them.

It sounds like you just copied just the MXF clips so you will now have to find a utility that can convert them to a format that FCP can read.

I have P2 and if you copy the entire directory structure it will read OK even if you have copied it to another storage device.

This footage had to be "recovered" from a faulty CF card. So, yes, I only have the MXF clips to work with. I can view them with VLC player but can't import them into FCP7. Can you recommend a utility that will be able to handle the conversion? Many Thanks.

Do you have CS5?
You could import the MXFs to Premiere and export to ProRes.
I had a situation last year where i had 120 clips to convert and ended up importing, copying the project after inserting all clips into the timeline, duplicating the project which stripped out irrelevant files and gathered the MXFs to one folder. Then converted with Media Encoder to ProRes. It was the only solution i could find without spending more money on software.