PASTE TEXT

Use a keyboard command via System Events to paste the selection from the clipboard

tell application "DEVONthink Pro"
	activate
	set the clipboard to "Text To Paste"

	tell application "System Events"
		keystroke "v" using {command down}
		delay 0.5

	end tell
end tell

This is a normal paste. The contents of the clipboard will appear at the selection point. Selected text will be replaced.