Mortama created a "guide" on
Ripping zones
In addition, editing the textures is basically limited to Changetex (export, edit, import)
An example of an modified Whitegate by Pixelpink over at ffxidats.com (
thread )
also a Windurst mod he is working on
You can also HQ furnishings/zones without VRS, just need a lot of patience, Changetex, and a hex editing program. Nomido's
HQ Textures in Moghouse, Furnishing and Effect Guide