Live Trace batch from Adobe Bridge

Not sure if this is, stricktly speaking an Illustrator question but I'll start here. You'll see.

A month ago I was at the videoforum over here in the Uk watching lots of cool demos of the Adobe Production studio.

Well, they showed this really cool thing where you export your movie from Premiere Pro as stills and then from Bridge you can batch them through Illustrator's Live Trace fucntion to sort of cartoonise them. This produced a whole bundle of new files which were then brought back into Premiere as a numbered sequence and looked great when played back.

I thought I had remembered how to do this but it's just not working how I want it so I'm assuming I have something wrong somewhere. the batch job though Illustrator (from bridge) is working but the resultant .ai files are all A4 portrait sized and not suitable for video at all. if I go into Illustrator and change the size to my source files to be 1440x1080 (HDV) then 'save as' it's ok.

So how can I get .ai files of the right size out of Illustrator? Anyone see this and can remember how to do it?