Hey @CJK,
I'd say it should be.
Here's an example of creating a webarchive from remote content:
Create a webarchive file of a given web page (search disabled).scptd.zip (15.2 KB)
I think this might be the same basic code:
Create Web Archives (Download Web Page) from a List of URLs
A related Unix executable:
Download a complete webpage without opening
These don't get us into the DOM, but I expect Shane can explain how to do that.
-Chris