[Brian]

It sounds like you want something like the following. Once you have all the documents open, this will cycle through them and execute the code in the inner section for each. Hope this helps!

tell application "OmniOutliner Professional"
	repeat with aDocument in every document

		-- e.g. the stuff you want to do goes here 
		set text of cell 2 of row 1 of aDocument to "hello"

	end repeat
end tell