i tried that and i said: could not find bglcomp.exe
If you have FSX Deluxe or Gold, you get the FSX SDK with it. I'm not sure how it goes with Gold, but with Deluxe, when you install the SDK, you get Gmax and its help, tutorial and library files. Once you install SDK SP1a, it removes those files, so you need to grab them before they get deleted (I COPY and paste them to another location).

As far as I can remember, you Export them from Gmax as an MDL file, then change the file extension from MDL to BGL. E.g. export as scenery.MDL and change it to scenery.BGL Or maybe you open them with bglcomp.exe (drag and drop ON bglcomp.exe) and it converts it for you!

Start Gmax using the FSX_GMax shortcut, by copying and pasting it to your desktop, that way the FSX Gmax scripts get started when Gmax starts.

Mark