If it doesn't pertain to EverQuest UI's, then this would be the wrong place to ask
The Sims 3 has their own community about modifications, specifically at
www.thesims3.com, under the community forums. You can also check out
www.modthesims.info and inquire about it there.
I too own Sims 3, but there really is no reason to alter the UI, IMHO.