As far as I know you cannot. That is why I switched back to the stock browser. I like double tap zooming better then pinch and zoom only. Mainly because I can surf with one hand. I will switch back when you can use both. Other then that I think Dolphin is a better browser because it has many features not included in the stock one.

 

Add me to the list.

I liked Dolphin but missed double-tap zoom too much to stick with it.

 

Yup, same reason why I don't use Dolphin except for very specific situations.