It is possible. In the code below I have colored the part that should be added.
Code:
<Page AbsorbsInput="false" MinimumSize="0,78" Name="v1" ScrollExtent="166,78" Size="166,78">
<ImageStyle Filter="true" Name="AAExpAvailable">
<ImageFrame Name="image" Source="images/icons/aa_active_icons.dds" SourceRect="40,39,62,62" />
</ImageStyle>
<Image AbsorbsInput="false" BackgroundColor="#00FFFF" Location="124,1" Name="AAExpIndicator" PackLocation="cpc,top" PackSize="fixed,fixed" ScrollExtent="12,12" Size="12,12" Style="Target.v1.AAExpAvailable" />
The code should be put in the following files.
eq2ui_mainhud_target.xml
eq2ui_mainhud_impliedtarget.xml