I've got this working on the detail page as I suggested with the repeating selection. Quite easy. Recordset:
FROM items, genres, itemgenres
WHERE itemgenres.ItemGenreItemID=items.ItemID AND itemgenres.ItemGenreGenreID=genres.GenreID AND itemID=varItem
varItem = $_GET['ItemID'] (from the URL variable)
But it would still be good to include this in the how-to.