using namespace System::Collections::Generic;
generic<class InnerT> public ref class MyList : public System::Collections::IList, IList<InnerT> {
  // ...
  property InnerT default[int]{
    virtual InnerT get(int index);
    virtual void set(int index, InnerT item);
  }
}

property Object^ System::Collections::IList::default[int]{
    virtual Object^ System::Collections::IList::get(int index);
    virtual void System::Collections::IList::set(int index, Object^ item);
  }

property Object^ default[int] = System::Collections::IList::default {... }

property Object^ IListItems[int]{
    virtual Object^ get(int index) = System::Collections::IList::default::get;
    virtual void set(int index, Object^ item)  = System::Collections::IList::default::set;
  }

T System::Collections::Generic::IList<T>::get_Item(Int32 __gc* index)
{
   //
}

void __gc* System::Collections::Generic::IList<T>::set_Item(Int32 __gc* index, T value)
{
   //
}