Hi,
Not that I have any experience with the 'bees, but if what comes out of them is just the serial signal put into them and there's no handshake, neither at the 'bee, nor at the SCC, then all you'd need should be a few components to deal with level translation (SCC claims "true RS-232 levels", which means they're bipolar) and I guess the 'bee is unipolar.
If, on the other hand, a handshake is expected...