It's not possible to control ws4gl from a script. The main goal was
to create a user friendly guy so it would be easy to use.
But it would be easy to create a controller in java to provide such
functionality. Remember that Studios are meant to pre-configure your
broadcasts such as timed layouts in the recent beta releases.
Seeking is not yet available in a layout, but can be done manually
using a slider. That's something I was considering as when entering a
new layout, you could seek the entry point in a movie... The duration
is already done by setting a duration on a layout, a bit like chapters
on a DVD...
Could you elaborate on what you are trying to achieve by using
scripts?