Is there a way to completely disable Dock?
This article from Lifehacker.com.au suggests setting the Dock autohide delay to 1000 seconds, like so:

defaults write com.apple.dock autohide-delay -float 1000; killall Dock


To restore the default behavior:

defaults delete com.apple.dock autohide-delay; killall Dock


The author says he sets the delay to two seconds, so he can still get to the Dock in those rare cases when it's needed.