I have done a similar thing few years back when I was working with Compact Environment.
I dont think any layout panel is available in Compact Winforms. So you need to calculate the postion programmatically yourself.
Rather if you are making the UI from an xml file, why dont you store the exact location where the textbox will appear on the screen as well.
Whatever you do, just create one general function (like public Label getLabel()) for each control, which will return the control for you, so that it is easier to manage the UI.