Re: ~! How do you wake people up?
First of all pray to Allah to make it easier for you in making them realize that Namaz is better than sleep.
Put the alarm clock to maximum volume and hide it under the bed at the cornor. Also hide yourself behind the door. It would give him enough exercise till he is able to find where the clock is placed. This exercise would help in removing his laziness.
One a serious note. Turn on the lights, turn off the fan and tell him " If you say Auzubillahiminashaitan....." the devil would no more be able to tempt you and it would become easy for you to get up. Just pray namaz and than you can go back to sleep as much as you like. There is a hadith that it is better that you lose all your possesions than to miss one prayer intentionally " (Give him an impression that you are not going to let him sleep no matter how long it might take unless he offer namaz)