Configuration bits (also known as fuses) can be configured using `__code' and `__at' modifiers. Possible options should be ANDed and can be found in your processor header file. Example for PIC18F2550:
_PLLDIV_NO_DIVIDE__4MHZ_INPUT__1L & [...];
static __code char __at(__CONFIG1H) configword1h = [...];
static __code char __at(__CONFIG2L) configword2l = [...];
//More configuration words