It sounds like you are just needing to use the scanned in item as a graphic and then draw on top of it. I've done that via the following: First scan it into an image (e.g. .jpg) and then, from AS, insert it as an image into a drawing. Draw the box whatever size you want it (e.g. the whole drawing) When drawing over an image, there are some things to click to decide which one is "in front"; you'll want the lines in front/on top so that you can see them. I keep learing and forgetting where to "click" for that but it's there. Also, sometimes I first lightened up the image in some image software (e.g. Gimp, photoshop) to make it easier to see the lines on top of it.
Hi I have used ScanVector for situations like this, , , takes a bit of time to clean up the scan to vector, but well worth it There are other types of programs for this also