Get extent from shapes

I'm trying to get the viewable extent from the pushpins I plot on the map.  In the MS VE version I was able to do it using the latlong <list> and do a Map1.SetMapView(lstData);  How do I go about doing it with this control?  I see the MapView is looking for a rectangle but how do I set the points xy, xx, yx, yy at the time of creating a pushpin?  Is there a better way to do this?

thanks

rich