JavaScript for a Loop between pages

I am trying to get a PDF to loop between 2 or more pages in a PDF, preferably to work in non full screen mode, unless fullscreen can be forced in both Reader and Pro?

The PDF is say 20 pages but I am only after 2 pages to loop with a time delay between them of say 5 seconds. I have found and tried the following script but it loops the whole document

app.fs.timeDelay = 5; // delay 5 seconds
app.fs.useTimer = true; // activate automatic page turning
app.fs.usePageTiming = true; // allow page override
app.fs.isFullScreen = true; // go into fullscreen

Help would be much appreciated