change text frame horizontally (text area) with script?

Hi there,

I've posted this question at InCopy Scripting but I've seen that many answers there are unanswered and since someone with InDesign knowledge may be able to help, I decided to also post it here.

I'm trying something that might be simple but am not being able to solve... When I am inside a document I created (or one that I've opened), I want to be able to change the text frame horizontally.

What I'm trying to do is exactly what I can with File > Document Setup > Text Area - Width. If I shrink this number to, say 60 mm, the result is exactly what I want. But I haven't been able to find a way of doing it via javascript...

I have tried the sample scripts for an answer or this forum or the internet, but I don't know how to do it. And I have that feeling it is quite simple... Maybe by creating a script menu action? For example, if I call a:

app.menuActions.itemByName("Document Setup...").invoke();

I end up at the same place than the menu option - but if I can inform the parameter via script and not use the menu interface, that would be it.

Of course, if there is a better way of doing it, it is also welcome!

I'm using InCopy CS4.

thanks!