What target and implied target mod are you using? I was going to post the two mods for you but the default seems to have this already.
Any ways..
You can do this in the UI builder BUT the UI builder is evil when it saves because if you mod has some tricky includes it will merge them with the parent object such as the mainhud. So I'll leave it up to you to use it or not.
The best way would be to open up eq2ui_mainhud_target.xml in notpad or what ever you use to edit text. Search for the key word v0. Once you find that scroll down to you find ;
Code:
<Image AbsorbsInput="false" AutoSize="true" BackgroundColor="#00FFFF" Location="14,0" Name="TierIndicator" ScrollExtent="132,15" Size="132,15"/>
Yours my not be the same but look for the key tags <image and name="TierIndicator".
Once you find that copy that entire line. ( if word wrap is on it my be on two lines just depending on your resolution)
Now that you have that copied, do another search for key word v1. Once you find that go to the very next line and press enter to make a new line. Now place your cursor at the start of that new line (it should be an empty line) and paste. That should put the TierIndicator in v1 (simple con mode).
Now save this file and do the exact same to eq2ui_mainhud_impliedtarget.xml.
Be sure to make a back up of your files before editing, just in case you FUBAR it:P