They might SAY that but they and secretly want to SEX you up. When it comes to girls judge them by their ACTIONS not their WORDS. Read the book of pook and weapons of mass seduction, then you will 'get' it.
I think you are looking for people to FEAR you rather RESPECT you. There's a difference. If you want to get 'don't mess with me' imagine going them go to the gym and take a martial arts class. When you are huge and have a blackbelt no one will mess with you will they? But it still will not make you the alpha male just by that (it will help of course).
There's no point me writing everything down when there is already great material here to read. I'll give you some basic points:
-Be a leader
-Be loud, talkative, funny and interesting
-Increase your physical presents (through what I said above and posture)
-Do something that people will respect you for
-Don't be phased when people poke sh!t at you
Of course this advice might not be the best because I'm not THE alpha male, even though I do a lot of the above I am still small and don't actively seek it. Nevertheless I score when I want with whoever I want. I think I will be there sometimes soon anyway.
OH: When I say I'm not THE alpha male it is because my main friendship group is basically a group of jocks and alpha males. In my other friendship groups I am THE alpha male.
...Apligies, I started rambling there
If you don't want girls to thinky our an @ss hole then don't act like one.