Slowing the Day/Night cycle

So I've been trying to find a plugin for my Bukkit server that will allow me to edit the speed of the day/night cycle. I want the end result to make it so the entire cycle is two hours long, or 6 times slower than the original 20 minute cycle.

I've tried this plugin called ProperTime, and with enough messing with it, it DOES do the job, but not very well. Rather than the sun moving slowly across the sky, it moves at regular speed and keeps jumping backwards. This produces a strobe-like effect at dusk and dawn, which is rather annoying.

Anyone know a plugin that can do this, and allow the sun/moon to move at a constant slow rate?