Program a single modem chip without AT-Cmd?

Hi,
I need help urgently, a project need to use a single modem chip CMX624, which cannot accept AT-commands directly, so I need to control modem's built-in register like SETUP, TX_TONES, TX_DATA, FSK_MODE. But right now,I really dont have any ideas on how to use C to implement it.

Any one have done this before? Just give some hints or example codes. Thanks