You could always use Acronis to load an image on a machine (register it to FOG and load your image from Acronis) but BEFORE booting the OS (that way you won’t have to sysprep again), upload the image to FOG. This would make an exact copy of your current set up and load it to the FOG server in a format it can understand.
I realize that this is very cumbersome if you have multiple images, but it is a work around 🙂