My problem was that my original image was a flat file, not a path. This meant that following @www.Flextras.com's answer didn't work for me, the result was an FXG with an image embedded.
The process I used is as follows, I used Adobe Fireworks for this:
1) Magic wand selection
Select the body of the image with magic wand.
2) Convert to path
Right click -> Modify Marquee -> Convert to Path
3) Export as FXG
File -> Export
4) Done
Open the FXG in notepad and extract the path data.