Does the SCI port only support RS-232 interface?
SCI is Freescale's way of saying UART. The interface is UART and nothing but UART. Add a RS-232 transceiver to a UART port and you get RS-232.
All HCS12 devices have both SCI and SPI. Pick either of them, depending on what the Bluetooth chip supports. SPI is generally to prefer for on-board communication.