Excel 2008 AppleScript question

My script will manipulate a set of contiguous rows selected by the user before the script is invoked, like this:

tell application "Microsoft Excel"
	get address selection
	if [condition] then
		[manipulate the rows]
		tell application "Finder"
			error "No row(s) selected"
		end tell
	end if
end tell

but I don’t know how to test to verify that the selection consists of one or more contiguous rows.

Moving to OS X.