Binding Arrays With Missing Elements In Mvc?

I am trying to bind a dynamic array of elements to a view model where there might be missing indexes in the html

e.g. with the view model

class FooViewModel
{
public List<BarViewModel> Bars { get; set; }
}
class BarViewModel
{
public string Something { get; set; }
}

and the html

<input type="text" name="Bars[1].Something" value="a" />
<input type="text" name="Bars[3].Something" value="b" />
<input type="text" name="Bars[6].Something" value="c" />

at the moment, bars will just be null. how could I get the model binder to ignore any missing elements? i.e. the above would bind to:

FooViewModel
{
Bars
{
BarViewModel { Something = "a" },
BarViewModel { Something = "b" },
BarViewModel { Something = "c" }
}
}