Thanks for replying guys, however I still believe that they may used an external tool for some features.
I unpacked the 4th mission with a pff editor and with my bms2mis program I was able to edit it. My questions here is:
Is this possible for MED? I mean, no one can see what's happening there (it's the garage).
So that's why I am still confused but it seems to me that they have used a 3D Editor
Any suggestions about this?