I am having similar problems. I keep getting an object does not support this method error when trying to capture the VIEWCTR system variable value. I am also running into errors when trying to do a zoomextents. I have upgraded to Pro4 and none of the help menu examples will display even after updating my browser.
I have posted some code in response to Cheryl's algorithm and I split the zoom into a separate Sub so you can have a look at it and use it in your code. It is really just the Help Example with some adjustments.