Just rename builin-res.jar and amber-res.jar to keep them as backups, then download the zip and extract the 2 jars into your client root folder, restart the client.
These may cause the client to crash in the future if new res are added in updates, I'll be looking for a more future proof option but while I'm playing for now I'll update when that happens.
Worth noting that the top bar of windows isn't entirely selectable without a tiny client edit which I cba to do, just drag it via it's title.
Also worth noting I haven't been able to test entirely with recent UI adjusting changes in the last 3 years as I've only been playing a couple of weeks and couldn't finish any Credos but I expect it'll be fine.
Also Armor Class is almost invisible in the paperdoll, I'll possibly fix this, but no assurances.
Example:
Download: http://protectorworld.com/files/hnh/hnh-custom-ui.zip