I just found out that you can make your osx dock immutable, that is, you can set your dock so that nothing else can be added or removed!

open terminal
type in

defaults write com.apple.Dock contents-immutable -bool YES
killall Dock

thats it! you will now be unable to add or remove anything to / from your dock!

to make the dick mutable again (to enable you to add and remove items again)
open terminal
type in

defaults write com.apple.Dock contents-immutable -bool NO
killall Dock