PIC10F200 internal clock
The compiler cannot 'auto calibrate' because it has no idea what frequency an individual chip may run at. The chip programmer/debugger could do it by downloading and running a program in the PIC which produces a frequency on an output pin. Then this frequency could be measured, and the required OSCCAL calibration value calculated and inserted into your code.  

Normally you don't need to do this because Microchip has already done it at the factory. A calibration byte is stored in the last ROM location in a MOVLW (MOVe Literal byte to Working register) instruction. On power up or reset the PIC executes this instruction, so the W register has the calibration byte in it on startup. Your startup code just has to save this value (before any other code that uses the W register!) and write it to the OSCCAL register. 

Factory calibration is probably not as accurate as it could be because it is done quickly and not in the exact circuit you have. You might be able to get slightly better accuracy with a PIC program that incrementally sets OSCCAL to different values until it gets as close as possible to the required frequency (perhaps by comparing it a reference frequency on an input pin) then tells you what calibration value to use. Here's an example:- 

Internal Oscillator Recalibration Utility 

(Note: the project in that link only works with the 12F629 and 675. The 10F200 has no EEPROM, so you would have to use some other method of extracting the calibration value, eg. send it as serial data on an output pin.)

But 7 days is 10080 minutes. The PIC10F200 has an internal oscillator tolerance of +-1% at 3.5V, which corresponds to +-100 minutes in 7 days. So even with the best calibration you cannot guarantee to get an accuracy of 'a few minutes'.