Instance Switching is swapping the adt files for instances, so like instead of zoning into Zul'Farrak, you can zone into Old Hillsbrad Foothills. This tutorial will teach you how to do that.
First you'll need a few programs.
MyWarcraftStudio - (http://www.curse-gaming.com/en/wow/a...aftstudio.html)
BatchRenamer -(http://batchrenamer.sourceforge.net/)
MPQMaster - (http://www.wc3sear.ch/?p=Tools&ID=94)
First, go to your World of Warcraft folder, go in the Data folder, then create a folder and name it World. OK now go IN the World folder and create another folder and name it Maps, ok now go IN that folder and name it SchoolofNecromancy(also known as Scholomance). Ok now open MPQMaster and use it to open Terrain.mpq in your wow/data folder. Ok now open the World folder you see, then open the folder Maps that should be inside of it and scroll down until you see EmeraldDream.
Now open EmeraldDream and select all the files in it, right click and select Extract, now find the folder you made earlier in your wow/data folder, go into World\Maps\SchoolofNecromancy and extract all the files into it. Ok now close MPQMaster and open your BatchRenamer, go into your wow\data folder, go into the folder you made earlier World\Maps\SchoolofNecromancy. Ok once you have that folder open, in the top left corner of your batch renamer you should see 2 boxes, in the first box put EmeraldDream, and in the second box put SchoolofNecromancy, then click Go and swap em.
Ok close your batch renamer, and now open MyWarcraftStudio, click Pack(P) and then Create MPQ Archive, now just put in something like speech2 or patch-4 and click Ok. Now click Pack(P) again and click Add File to Archive. Now click the little three ... on the side of it and find a random file in the World\Maps\SchoolofNecromancy and click it. NOW DONT ADD THE FILE YET, it should say the file name in the little box, now before the file name add World\Maps\ before the file name and then add it. Ok now in the box on the left you should see a folder called World, open it, then open the folder called Maps, right click the Maps folder and click Import Folder, find the World\Maps\SchoolofNecromancy folder and click a random file in it and import the folder.
After it's imported find the file in the Maps folder in the box on the left that ISEN'T in the SchoolofNecromancy folder, select it, then right click and Remove File.
Ok close MyWarcraftStudio and open World of Warcraft and zone into scholo, you should fall into some green textured area, tada you just instance switched. (if this didnt happen then you probaly switched emerald dream with scholo and not vice versa, meaning if you tried (if you could) to zone into emerald dream, it would be scholo.
Here are some instances that fit together.
Scholo - Emerald Dream
Zul'Farrak - Old Hillsbrad Foothills