How can i change map picture?

You know how some maps, (Spellcraft, Porn games) have a picture for their map in the waiting room for the game? Is there a way to add a custom picture to that inside UMSWE? because you can change the loading screen but i guess you just can't change the map picture inside it ,
Thanks in advance
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PS don't tell me to open up Tech MPQ cause i'm not going to screw with that ****, i hate doing it every time.