Yes. you can do that.
Override sublayout(init,int) of your screen class:
PHP Code:
public void sublayout(int width, int height)
{
super.sublayout(width, height);
setExtent(100, 200);
setPosition(10, 20);
}
Now play with the numbers a little bit to achieve what you need.
( Remember that you can use Display.getWidth() and Display.getHeight(); )