How to use AD6 & AD7 in "Arduino Mini"

Hi! I know M168 have 5 PWM(D/A) , and I don't know how to add the other 2 PWM in :

int analog_out_pin_to_timer_array[NUM_DIGITAL_PINS] = {
      NOT_ON_TIMER,
      NOT_ON_TIMER,
      NOT_ON_TIMER,
      // on the ATmega168, digital pin 3 has pwm
#if defined(__AVR_ATmega168__)
      TIMER2B,
#else
      NOT_ON_TIMER,
#endif
      NOT_ON_TIMER,
      NOT_ON_TIMER,
      NOT_ON_TIMER,
      NOT_ON_TIMER,
      NOT_ON_TIMER,
      TIMER1A,
      TIMER1B,
#if defined(__AVR_ATmega168__)
      TIMER2A,
#else
      TIMER2,
#endif
      NOT_ON_TIMER,
      NOT_ON_TIMER,
};

If Arduino 06 can add these new AD and DA to soft , it will be better!