SPI wiring SDIO pin with MISO and MOSI
It appears that this RF module doesn't exactly follow the SPI specification. This means that you probably won't be able to use a canned high-level driver. Some of this is speculation based on a SPI slave module that I found that uses a bidirectional data signal.
SPI Slave Selects (AKA Chip Selects) are basically simple MCU outputs, so creating a second SS should be easy.
Connecting MISO and MOSI also causes complications, you must tri-state MOSI during the part of the cycle when the slave is driving SDIO.
MPU        SLAVE
SPCLK      SCLK
MISO/MOSI  SDIO
SS1        CSB
SS2        FCSB