I found an old GUI package named AO Omni Terminal GUI Version 1 and old launcher skins at internet archive.
https://web.archive.org/web/20030401183205/http://www.agentsector.com/agentsector/files.html
I uploaded a copy of the gui .exe to https://archive.org/details/ao_omni_terminal_gui_v1
You may find this interesting: https://web.archive.org/web/20021010114948/http://ultima.lightning.net/ao/