How do I specify the Data source and XPath binding in WPF

In another context, I'm able to use

<W3V:FeasibilityPage DataContext="{StaticResource mcf}" />

And then within that page I can do

<W3V:ObjectList DataContext="{Binding XPath=customer_requirements/mechanisms}" />

I want to combine them in one, to do:

<W3V:ObjectList DataContext="{StaticResource mcf Binding XPath=customer_requirements/mechanisms}" />

But this doesn't work.