What is the special tool needed?
 

What is the special tool needed to separate the chainrings. It looks like a screwdriver slot but I just know it takes a special tool.

Two tools: chainring nut wrench and allen wrench.

Yes.
http://img1.qbp.com/6SPsvm45/prodl/TL7461.jpg

or

http://img1.qbp.com/6SPsvm45/prodl/TL4816.jpg

I get by with the screw driver on my swiss army knife.

I gotta say that I have never needed anything other than a fingertip to hold the chainring nut. Once the allen loosens on removal you can just spin the screw out while putting pressure on the nut with your finger. On installation the reverse works fine. I have never had a problem with the nut spinning when I torque the bolt head once the nut snugs in.

I suppose my next rebuild could prove that wrong, but I've never seen a reason to buy a tool that does something I never needed.

Get the special tool, it doesn't cost much. I got one on sale at Performance a while back, I think it was less than $5.

Did Campagnolo or VAR, or someone else make one that's deluxe? I've had a Sugino one forever, but it's cheesy, and I don't like to hold it.

VAR made the best one ever.

http://www.sheldonbrown.com/var/pages/var0020.html