For the benefit of users reading this thread Rhys asked how he could learn to create gauges for himself. Here is my reply:
Rhys,
Firstly you will need to download the Software Development Kits (SDK) from Microsoft. As the FS2004 site is now archived its hard to find.. the best place to get the SDKs are from
http://files.fsnordic.net/Flight_Simulator/Miscellaneous/SDK/You'll specifically need the Panels & Gauges SDK.
All the info is here but its not user-friendly. The best source to understand it is to download Dai Griffith's tutorial
http://www.simviation.com/fsdesign_panels1.htm Look for Gauge Creation Tutorial Rev. 14
If you want to create XML based gauges then you will find tutorials at
http://www.fs2x.com/Good Luck
Regards
Jim