Bart, try using leather. A soft leather wrapped around a harder, yet still somewhat soft flat core. I think that in order to acheive that sound, you'll need a large ovular shape to the beater. Another thing that might be easier is to take that cowbell beater that you can buy. I think it is made by Regal. It's a normal beater, but instead of a mallet, it is a wooden stick at the end, with a rubber contact point. You might be able to wrap that with some medium weight soft leather. I would think that leather will be the best way to acheive that sound. Or maybe something a bit softer, like goat skin.
I KNEW someone was going to say that. I stopped myself from going into detail of what I have been trying, but I guess I shouldn't have.
I've already tried the Regal thing, in fact, talked to Regal about it at their booth for PASIC in Nashville.
I need to find a VERY soft goatskin to try. Actually the next thing on my list is to try a shammy, like what you use to wipe your care down after you wash it. The other trick is getting the area of impact to be the size of your hand. I need more surface area striking the drum.