Since it'd already not April 1st... here it is:
When you run StarCraft:BroodWar, you press the original game *.exe, or a shortcut that opens it.
By doing so, it quickly extracts the information from your StarCraft *.mpq files (while you see the loading message) and than the game starts running.
Even if you delete the *.mpq while the game is running, it'll keep running, because it's temporarly saved.
Now, mods, are *.exe files that has their own *.mpq and that *.mpq has all sorts of changes.
If you'll change the *.mpq in your StarCraft directory into the mod's *.mpq, it will keep running on the original *.mpq, just as if it was deleted (doesn't matter... the point is that it's gone).
So you'll have to either manually or by a program reopen StarCraft, means exiting and than re-opening, and than automatically entering bnet, and automatically entering the game you entered that activated it.
Unfortanutly, since the program runs thru bnet that you opened from StarCraft, as soon as it'll start it's procces it'll close your StarCraft and there it ends.
If you'll want it to continue, you'll have to put cookies on your temp files to do the rest of the process.
But if you'll start automatically downloading cookies from bnet, that runs thru an *.exe, the computer will detect that as a virus, shut down the program, and delete the cookie.
So actually, unless you create better editors that allow you to mod the maps themselves and not creating a new *.exe, changing mods thru bnet will be inpossible.
Please don't edit this post, it took me much time to write it...

And besides, as I said, it's not 1st April anymore, you shouldn't have abused gullible people here by telling them such a hoax from the first place... some might get shocked knowing it's not true (since everyone want that to be true).