Add Dynamic Inclusion Rules to group in Powershell

Hi, i need to create lots of groups based on Computernames.

I can create the groups with powershell with the script from here

http://blogs.msdn.com/b/rslaten/archive/2013/06/06/creating-groups-in-scom-2012-with-powershell.aspx

But i would like how to add a Dynamic inclusion rule to each group like:

( Object is Windows Computer AND ( DNS Name Contains TestComputer ) AND True ) 

Is there a way to do it?

Alternatively can i modify each group after creation and include this rule?

Setup is System Center 2012

Thanks