[dt192]

With a lot of help from lunarwtr (was mostly them), this markup seems to do it, assuming this is what you are talking about.

Best way would probably be to set BillboardField to x:0 y:0 width:3840 height:2160 then individually position each text element, keeping in mind that multiple can show at once and hide any you don't want by setting their x to -10000, else just position the whole BillboardField box as I did in the screenshot below.

<PanelFile ID="ID_UISkin_Billboard">
    <Element ID="QuestBillboardTextReference" X="0" Y="0" Width="600" Height="169"> </Element>
    <Element ID="BillboardField" X="112" Y="84" Width="800" Height="600">
        <Element ID="TerritoryText" X="70" Y="321" Width="659" Height="64"> </Element>
        <Element ID="AreaText" X="51" Y="440" Width="699" Height="64"> </Element>
        <Element ID="LandmarkText" X="17" Y="168" Width="767" Height="64"> </Element>
        <Element ID="DungeonText" X="200" Y="536" Width="400" Height="64"> </Element>
        <Element ID="PVPPermissionText" X="201" Y="41" Width="400" Height="128"> </Element>
        <Element ID="GenericBillboardText" X="-19" Y="232" Width="840" Height="91"> </Element>
        <Element ID="QuestBillboardText" X="99" Y="41" Width="600" Height="128"> </Element>
    </Element>
</PanelFile>

Here's the layout as visualised by luna's tool.



Here it is with the BillboardField box just top centered in game.