Why do you want to?
The reason you're doing this uncoupling is (I assume) to enable you to switch out the data tier at a later point, without having to modify anything in the Web project, and as little as possible in the Business project. To accomplish this, you should make sure that all your classes work against interfaces, rather than against concrete implementations.
In your example, you should probably define a Repository interface of some sort, which includes an Initialize() method. You then create a class (perhaps your specialized DbContext) implement the interface, and you work against that. In the Initialize() method on your repository, you call Database.SetInitializer() and thus you never have to reference System.Data.Entity in either the web or business projects.