I'm not sure most of the *.XML files go to the gauges folder inside of another folder,and about the other thing theres one particular prgm Named Flight Simulator Scenery Creator
I use it even is not so compatible there're few trickies to set things in FS9 to edit and set buildings and airports
It's very Friendly It's A FREEWARE and you must download AFCAD 2 if is anyone  diasagree,  It's my simple opinion

Hi Musnkatz. There are 2 basic types of XML gauges. The ones like the defaults are in CAB format & look just like zipfiles. Don't unzip them but paste the CAB files into FS9\Gauges. You should see some similar files already in there.

Some 3rd party XML gauges are configured in a folder instead of a CAB file. This folder will contain one or more XML files & BMP files. To install this type of gauge paste the folder itself into FS9\Gauges. The folder name must be correct or the gauges will not work.

Hope this answers your question.

PS. For the scenery check out the Scenery & Panel Design forum.

You're welcome. Gauges included with most aircraft will be in a folder (or zipfile) named Gauges or similar. This can contain any number of 3rd party gauges in various formats. I've seen some downloads with a selection of all 3 types - the standard GAU format + both types of XML gauges I described in my earlier reply. I find the best method of installing the gauges is to open this folder, click Edit/Select All & paste the complete contents into FS9\Gauges.

It should be easy enough providing you know how to recognise gauges. The folder & 2 files in the right-hand window in this shot are all 3rd party gauges.