All right, I've got something here that most of you (a.k.a 90% of you) will find useless. This is actually useful if you are using the second floor of the Pokémon Centre in your hack. I personally am, however I have edited the map to remove the Union Room, as even VBA-Link can't simulate the Wireless Adapter properly. As a result, I have moved the Direct Corner, so when exiting from the Colosseum room/Trade room the little door thing appears in the wrong position. After a bit of searching, I found out that the script ran exactly after the big door closes behind you is at 0x081BB34F. Or, if you're just interested in the setmaptile command, it is at 0x081BC03E. I hope that this is helpful to at least one hacker who isn't me.
Edit: Oh yeah, I forgot to clarify that these are actual scripts that can be edited with XSE.