Switch beetween CPU/GPU Rendering in Silverlight, XNA

[konraddo]

Hi, does anybody have an idea how to switch between CPU and GPU rendering in silverlight project that uses XNA? i found one tutorial, but it works only for non-silverlight XNA, as SL version of one of XNA dlls does not contain necessary methods..
I am talking about this tutorial:
Riemers XNA Tutorial > Run XNA on older pcs
Thanks in advance.