Numpad LED on PS/2 Keyboard

how to make the numpad led (num lock led) blink ?

to arduino is connected a standard ps/2 keyboard .... i use the PS2Keyboard.h library....

There is an extended PS/2 keyboard library which will help you as it has the LED features and extra keys. I can't for the life of me find it at the moment but it is around. Keep searching and you'll find it.