Setting a spinner divider for one specific spinner

I've recently been looking into customizing the divider colour between items in a Spinner's drop down list, and I found the way to do it for all spinners at once via the application theme. For example:

<style name="custom_divider">
    <item name="android:divider">#FFFFFF</item>
    <item name="android:dividerHeight">5dp</item>        
</style>

<style name="holo_light_dark_action_bar_custom_dropdown" parent="@android:style/Theme.Holo.Light.DarkActionBar">
    <item name="android:dropDownListViewStyle">@style/custom_divider</item>                              
</style>

What I want to do is style the dividers for one specific spinner (in this case, the spinner in the action bar), rather than all spinners. I haven't seen any solutions for that, so I'm hoping it's something obvious and that I just missed it. :)