Are there any 'rules' for setting up the search/scent square?
In my dim and distant past I can only recall that the size of the sqare had to meet certain specs and that the square was 'clean' apart from the articles thrown in. In practice the square was never foiled and articles tossed in but someone told me recently that the steward walks all over the square before placing the articles where instructed by the judge. So, quite a change!

What is the accepted way now?

The articles must be placed, not thrown, and yes the steward does walk in the square to place the articles. This has been the rules for the time I have been around trials, but that is only approx 12 years.
You can download a rule book from the KC site, or buy one in hard copy, think they are about £1.50.