Xtreme has the exact same per page widget area system as Weaver II pro. You must have the Companion plugin Weaver Xtreme Theme support installed.
You create your custom Area widget by giving it a name in the box at the bottom of Main options > Sidebar and Layout page.
You populate your newly created widget Area in Appearance > Widgets.
Then on the page that should be using that custom Widget area, you select the name of your widget area in one of the drop down list located in the Widget Area Replacement section of the page editing page.
If you are having a problem with that, please be specific about what you did and give us a link to the page