[whpalmer4]

I know you can change it for an entire cell. An example:

tell application "OmniOutliner"
	tell front document
		set color of text of topic cell of selected rows to {0, 0, 65535}
	end tell
end tell

This code changes the contents of the topic column for the selected rows to be bright blue. I don't know how you can grab just the portion of the cell that is selected, however. What does your underlining setup look like?