There's two issues here:
1. Making an image of the disc, using the files/folders you drop into the UI.
2. Burning the image onto a disc.
My library wasn't meant to do the first step without a UI; in fact, the library was only meant to help you with step 2, because this isn't meant to be an implementation of a file system but an implementation of the SCSI interface.
I suggest you take a look at the "How it Works" section in
http://www.codeproject.com/KB/system/SCSI.aspx for burning the image, but the library currently can't help you with creating the image without the UI.
If you'd like, you can tweak the BackgroundBurner class by hand to make it independent of the UI, but because the library wasn't designed for creating an image, it's not useful for that task as-is.
Sorry if that's not the answer you were hoping for.