MSHTML, from C++, force the selection of an element

Using MSHTML from C++
When design mode is activated, and when the user
clicks on an element which has "absolute"
position , a resizing-rectangle is drawn around the
position of the element.
How can I force any element to be selected that way
from my C++ app ?
In other words, I have the pointer a IHTMLElement
of the page, how can I force it to be selected in design mode ?
I've tried around with IMarkupServices, IMarkupPointer,
IMarkupContainer, IServiceProvider, IHTMLEditServices,
but I cannot force any element to look selected in design mode,
without the user clicking on it....
Can you help ?