I choose to just be better at my job. I'm lucky though. I work in an industry where performance can be measured. I finish projects faster, I'm more efficient, and customers seem to like me when I work with them. I get to lead other developers because of this.
I think the asshole based promotion only exists in jobs where people don't actually produce much. (By choice or not) I don't know a whole lot of bosses in real life that would take a scheming dick over a really productive employee for a higher position.
Edit: I think there needs to be a defined difference between total push over and someone with a conscience. You can be assertive without actively being a twat to someone.