This property is not exposed in Styler, or wasn't last time I checked. To add that property you will want to do an "APP source edit" (sometimes called APP override). The easiest way to do that is to add a Property Set called, for example, "fixOrphanLines". You right click "fixOrphanLines" and go Edit Source.
In there you will want to add the code that is required. I don't know the incantation off the top of my head. You need to figure out what the current block object is, go to it's defaultParagraph, and set the orphanWordLength property. Something like:
formatting.currentBlock.defaultParagraph.orphanWordLength = 10;
// or perhaps
formatting.currentParagraph.orphanWordLength = 10;
You then have to associate that Property Set with all the contexts in the stylesheet you want that behaviour.
If you require more detailed assistance there are organisations that can help. The company I work for (www.gpsl.co) is an example. We are specialists in Arbortext and APP customisation, stylesheets and custom software development.