Place all the .xml files in a directory of the /ui folder where default is located. Then all .dds files that are images go in a folder off of your /mod folder. Any Icons go in a /icons folder of off the /mod/images folder.
Here is my directory tree:
ROOT (whatever drive you have EQ installed on mine is E
---eq2 (name of game folder)
------UI (This is where the game gets all UI info)
---------Mods (I made this folder for my MODDED files I want)
------------Images (Must be here for custom images to work w/modded files)
---------------Icons (As with Images custom icon files must go here)
In your GAME directory (ie: ---EQ2) place a file you make with notepad called EQ2.INI Here is mine for example:
cl_letter_box_position 0.999
cl_ui_skinname mods
cl_ui_subdir UI/
Now, the game knows where your mod folder is. The letter box is NOT necessary!! I used a custom mod that I did and I moved my Letterbox to the bottom. So, you would use the NEXT two lines. Just make sure they MATCH your Folder names YOU created.
Load the mods you like in to the folders as per the install notes found either in the zip (where it should be, and yea I forgot to add to few of mine). If no notes, check the file description on this site where you dl'ed the file and usually install notes are in the post (like mine).
basically any and all UI mods will follow the same install as I mentioned starting this response.
Once you have the files in place, if not already done so, EXIT EQ2 to desktop. Then, restart EQ2 and you should see your new changes.
Good luck!
-dn