When you want to install new image you can load your old image from hd then use Advanced SmartCopy option from flash wizard multiboot tab. It will copy settings by default plus you can specify any other folders you would like to be copied to new image, like /var/keys, /var/bin etc.
If you just want settings from hd image then you can go to config and utilities tab and use "receive and save dreambox services" button. That will copy channel settings to your pc. Then you load new image from usb and use "send all services now" button.