Enable/Disable Button On Ribbon When Content Type Selected

I have created a custom action button that appears on the DisplayForm for a specific content type.

On the list view I would also like to enable the button but only when the specific content type is selected and only if there is only one item selected.

<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="http://ift.tt/sQmbje">
<CustomAction
Description="Button Blah"
Title="Button Title"
Id="{53801DF2-A778-4E93-8191-ACBC06C7D4DD}"
Location="???????????????"
RegistrationType="ContentType"
RegistrationId="0x010014D754C688D12A4FB4C811B4B4F67A5C"
Sequence="0"
Rights="ViewListItems"
xmlns="http://ift.tt/sQmbje">
<CommandUIExtension xmlns="http://ift.tt/sQmbje">
  <!-- Define the (UI) button to be used for this custom action -->
  <CommandUIDefinitions>
    <CommandUIDefinition Location="Ribbon.ListForm.Display.Manage.Controls._children">
      <Button Id="{10C2173C-537F-4D3D-8394-9ADB8486CEBE}"
      Command="{99AAAD72-4AB6-4EC0-8B5A-E3F194145A4D}"
      Image32by32="~site/_layouts/Images/GCMS/SomeImage32.png"
      Image16by16="~site/_layouts/Images/GCMS/SomeImage16.png"
      Sequence="0"
      LabelText="Button Label Text"
      Description="Button Blah"
      TemplateAlias="o1" />
    </CommandUIDefinition>
  </CommandUIDefinitions>
  <CommandUIHandlers>
    <!-- Define the action expected on the button click -->
    <CommandUIHandler Command="{99AAAD72-4AB6-4EC0-8B5A-E3F194145A4D}" CommandAction="~site/_layouts/custompage.aspx?List={ListId}&amp;ID={ItemId}" />
  </CommandUIHandlers>
</CommandUIExtension>
</CustomAction>
</Elements>

How do I show/hide a button when a specific content type is selected in a list view?