Copy the files from the Gnomie-Stuff folder into the skin you use, in your EverQuest uifiles folder. Take only the windows you want; the player window needs player.dds with it.
To try them on the default UI, copy the whole Gnomie-Stuff folder into uifiles and type /loadskin Gnomie-Stuff. EverQuest takes every other window from the default UI.
The target and group windows show MacroQuest information, and the group window works with MQ2GroupInfo.