There are 2 main types of sponge baffling that I know of:
1. Using a sponge on the Outflow:
Baffling it like you would with a plastic bottle except you rubber band an AquaClear aquarium sponge that's big enough to cover your outflow over the filter and outflow.
You can also adjust the baffling power this way.
2. Using a sponge on the intake:
Two ways to do this:
A. In the intake vent: Cut a small part off of an AquaClear aquarium sponge and shove it into the vent (verry bottom bit that has the vertical slits) to where it completely covers the inside and is a tight fit. Then just shove the vent back onto the intake tube.
B. Over the intake vent: You could cut a hole in an aquaclear sponge and then shove the little vent part of your intake into it, then shove the intake vent back onto the intake tube.
Both baffle really well and act as a pre-filter/sponge filter. =]
Good luck with whatever you choose! =]