Smoothly zoom and scroll scrollview?

I'm using a scroll view to allow the user to pan and zoom some custom map images, but I can't find anyway to implement a nice 'my location' action.

I want to zoom and scroll the view simultaneously to a particular points, but there's two problems I'm facing.

1. The scrollTo method seems very unpredictable. I'm placing a marker at an x/y coordinate inside the scrollView, but when I scrollTo those coordinates, it goes to a different location every time?
2. The scrollTo and setZoomScale methods don't work in tandem, is there a way to zoom and scroll at the same time, as a map view would when you centre on the user location?