How to set scrollbar position on userobject programmatically

I have a user object that has several datawindows, one on
top of the other so that the cummulative height of the
datawindows is greater than the height of the user object.
Depending on the situation I would like to open the user
object with the user object scrolled to the lowest
datawindow.

How do you do programmatically position the vertical scoll
bar on a user object?  Something similar to the
verticalscrollposition on a datawindow?

Thanks