Would a .pdf work? If so, printing to .pdf offers the option to include line numbers in the output.
If not, how about Search & Replace with regex to insert line numbers? Wait. Won't work simply, as you'd have to count line numbers in the replace. But a macro to do the same should work. It's an iterative count of the line on the replace, so... (Think-think-think). Gotta think about it.
But .pdf is pretty nifty, and it works now.