I've found a way to get rounded corners with IE

[CK]

Okay so I've got it working with another site that I've set up, I was asking on help on how to get it looking like my forum (rounded corners). When someone suggested I upload this FILE and put the following code

behavior:url(border-radius.htc);

in the style sheet elements that I want rounded corners on.

So basically upload file to root and add the code, guess what? It actually worked. Here's where you can see it working http://tsps.us

So it was simple enough to get it working on the site because all I did was modify the index file, what I'm scratching my head over is how I would get it to work on vBulletin, where should I insert the code?