Set default fill color in InDesign?

We have a set of documents that have a base fill color of magenta for that document. I’m trying to figure out how to get my script to change that default fill color when the script first opens the document, to prevent weird things from happening. Only I can’t figure out how to do it.

From looking at the library, something like this appears like it would be what to do, except it doesn’t work:

tell application "Adobe InDesign CS3"
	activate
	tell document 1
		set the properties of page item default of page 1 to {fill color:swatch "None"}
	end tell
end tell

Anyone know how to set this?