This is a strat that I (adelikat) came up with only a few years after the game was released. It gets a sub 30 time without having to time a late punch (which only has a 1 frame window of opportunity). You continuously use the easy CS trick to keep the clock stopped as much as possible. Each series of rapid punches can be a maximum of 6 punches long.
While this strategy is possible in real time this movie is Tool-assisted and represents a frame perfect version of this strategy. It achieves a 23.97 time.