You can't, as far as I know. Tables just don't work that way.
If I just *HAD* to do this, then this is probably a situation where
I'd use the \r\n. But even then, I'd just be setting up myself for
failure because if I'm writing specs for such fine details such as
line breaks, the processing of that text is only going to get more
complex and it's not going to be very readable.
Just in case this helps: You don't have to use SpecFlow to test your
entire feature here. It's fine to use it as a way to demonstrate the
"main" scenarios that your feature is concerned about, and then leave
the finer details to unit tests.
Darren Cauthon