First, I would check with one of the paintless dent repair places... this sounds like a slam dunk for one of these guys... but it would cost you some...

If you really want to do it yourself... and if I'm reading this right (dent goes in from the outside of the hood down) What you'll need to do is maybe even wrap the dolly in a thin cotton cloth. (what ever will contact the paint) Then you'll lay the dolly just to the outside of the indent on top of the hood with say your left hand and hold it tight against the panel. Then with your right hand and the hammer, you start to lightly tap around the dented area... (never tap right where the dolly is as you'll be streching the metal and could warp it)

So in effect, the dolly is keeping the surounding area from going upward as youi tap, and the hammer is pushing the indented area back out...Work from the outside of the dent to the center. If you go right to the center, you stand a good chance of cracking the paint...

Keep doing this lightly, moving both the hammer and the dolly all around the indented area and inspecting it as you go... a little at a time.

It won't take much to get it back out, light taps are key, as if you tap with the edge of the hammer you will leave marks! So very light flat taps...

The paintless guys use a series of spoon type tools to sort of smooth and push the dent out from behind the dent, from the outside to the center of the dent. No paint cracks, and they just smooth the dent out...

Hope this makes sense and you can follow along?
Maybe practice on a piece of scrap sheet metal?

Good luck and let us know how it comes out!

Brett - 67 Drop Top 455!