Below is some information on using DSL-embedded.
DSL-embedded can share a hard drive with a common DSL installation by using the 5way script. More information on the 5way script can be found on a download mirror, inside the 5way tarball.
Unless you assembled your pendrive DSL/Qemu software other than the standard, you should already have the boot option qemu in syslinux.cfg.
This will allow access to the virtual harddisk as hdb when booting from BIOS.
You should see an entry in /etc/fstab which maps /dev/harddisk /mnt/hdb
When you backup/restore you do that to a device, the device for the virtual harddisk is simply harddisk.
This device should already be populated in the backup/restore gui.
To share your myDSL extensions use mydsl=harddisk
If you are running dsl-embedded then it is probably most desireable to share a common persistent
store between the virtual environment of Qemu and a reglar boot via BIOS. That would imply for both booting methods to use the virtual harddisk. This has been discussed before: See this thread