I was tinkering with my almost-finished KJFK 1972 scenery (btw will be uploaded soon) and I pulled up the default terminal 4 by accident using Instant Scenery. I noticed something that delightfully made my heart sink. There was the old 1970's IAB attached to it complete with textures! Just what I need! But its attached to the MDL file for the default terminal 4 (decompiled NewYork.bgl and opened up the Terminal 4 file, NewYork_50.mdl). I would love so much to utilize the IAB but I have no Idea how to "detach" the default terminal 4. Any ideas?

I don't know what tools you're using, but, you can use ModelConverterX, export the model to .3ds, convert the textures to 32 bit, import it into Sketchup, do what you need to do, export it from Sketchup as a .dae, import it back into MCX and export it as a .mdl. And use it in FS. However before you upload it anywhere you might want to make sure you don't violate any of MS copyright as people are quite touchy about that.