I wrote this code for the Microchip MPC3204 , and I imagine it will be similar to the Max186

=========================================
sbit ADC_CLK = P3^4;
sbit ADC_DOUT = P3^5;
sbit ADC_DIN = P3^6;
sbit ADC_CS = P3^7;
------------------------------------------
void adc_delay(void)
{unsigned char delay;

for(delay=0;delay<5;delay++);

}
void adc_init(void){

ADC_CS=1;//disable chip select
ADC_CLK=0;

}

void write_adc_byte(unsigned char output_data) {
unsigned char index;

for(index = 0; index < 6; index++) // Send 6 bits to the adc
{
ADC_DIN = ((output_data & 0x01) ? 1 : 0);
output_data=output_data >> 1; // Shift the byte by one bit
ADC_CLK = HIGH; // Clock the data into the adc
adc_delay();
ADC_CLK = LOW;
}


adc_delay();
}

unsigned int read_adc_byte(unsigned char channel ) {
unsigned char i;
unsigned int adcValue;

ADC_CS=0; //enable adc
adc_delay();

switch (channel) {

case 0 : channel=0x03;break;// single channel0
case 1 : channel=0x13;break;// single channel1
case 2 : channel=0x0b;break;// single channel2
case 3 : channel=0x1b;break;// single channel3
case 4 : channel=0x07;break;// single channel4
case 5 : channel=0x17;break;// single channel5
case 6 : channel=0x0f;break;// single channel6
case 7 : channel=0x1f;break;// single channel7
case 10 : channel=0x01;break;// diff channel0
case 11 : channel=0x0b;break;// diff channel1
case 12 : channel=0x05;break;// diff channel2
case 13 : channel=0x0d;break;// diff channel3

}

write_adc_byte( channel);

adcValue=0;


for(i=0; i<13; ++i)
{
ADC_CLK=1;
adc_delay();
adcValue= adcValue << 1;
adcValue |= ADC_DOUT;
ADC_CLK=0;
}
ADC_CS=1; //disables adc
return(adcValue);
}