Continuous Rotation Servo - self centering

I copied the code shown below from another thread and it works (couldn't get the normal servo sweep code to work). The only problem is that the code below doesn't start the servo from the same place each time. I would like to be able to get my continuous rotation servos to self center themselves at the start of the code. Is it possible using the technique shown below? Is it possible at all with a continuous rotation servo?

//Servo control via direct access to AVR PWM registers



#define servo1control OCR1A       // servo1 is connected to Arduino pin9
#define servo2control OCR1B     // servo2 is connected to Arduino pin10

//servo constants -- trim as needed
#define servo1null 3035
#define servo2null 3000
// Most servos are analog devices so the exact null point may vary somewhat device to device.
// This is particularly true of continuous rotation servos.

void setup(){
  pinMode(9,OUTPUT);
  pinMode(10,OUTPUT);
  TCCR1B = 0b00011010;          // Fast PWM, top in ICR1, /8 prescale (.5 uSec)
  TCCR1A = 0b10100010;          //clear on compare match, fast PWM
                                // to use pin 9 as normal input or output, use  TCCR1A = 0b00100010
                                // to use pin 10 as normal input or output, use  TCCR1A = 0b10000010
  ICR1 =  39999;                // 40,000 clocks @ .5 uS = 20mS
  servo1control = servo1null;         // controls chip pin 15  ARDUINO pin 9
  servo2control = servo2null;         // controls chip pin 16  ARDUINO pin 10
}


void loop(){
  // move servo for demonstration purposes
  servo1control = 2500;             // valid range is servonull +/- 1000
                                   //  - is counter clockwise
                                   //   + is clockwise
                                   // The difference from servonull represents servo angle or,
                                   //for continuous rotation servos, speed.
                                   //These values may differ somewhat unit to unit
  delay(1000);
  servo1control = servo1null;
  delay(3000);
  servo1control = 3570;
  delay(1000); 
  servo1control = servo1null;
  delay(3000); 
}

i don't think so because continues rotation servos either don't have their potentiometers connected, or don't have potentiometers at all, meaning the servo has no idea where center is, it doesent know any degrees, it only know when sent a signal over a certain value to spin one way, and below that value, the other way.

Hacking the servos usually involves removing the pot and replacing it with a couple of resistors.
If you replace the pot with a smaller pot mounted outside the servo instead of the resistors you can trim the servo to get it to stop at the same pwm signal. But to get it to start or stop at the same place in its rotation will need some more hardware attached to work out where it is.

Gordon