How do I get the front fog lights to operate without the regular headlights on?.

Have a 2003 Volvo S60. Relocating it to Portugal. Need to uncouple the front fog lights from the regular headlights. The fog lights need to operate independently from the headlights, currently they operate only together. The back fog light curently operates independently, which is OK. How do I get the front fog lights to operate without the regular headlights on?.