1. Firstly, have your 1.7 bin folder in the .minecraft folder. Keep it named bin.
2. Copy the 1.7 bin folder and paste it. Rename it to bin 1.8.
3. Go into the bin 1.8 folder and replace the minecraft.jar with a 1.8 pre-release one.
Now we need to do a bit of coding
1. Create a New Text Document in the .minecraft folder and open it up.
2. Type in the following text.
@echo off echo Welcome MC Change echo. echo Input one of the following numbers then press ENTER echo 1. Change to 1.7 echo 2. Change to 1.8 pre-release echo. set /p choice= Your choice: if /i %choice%==1 (goto 1.7) if /i %choice%==2 (goto 1.8) :1.7 cd \ cd %appdata% cd Roaming cd .minecraft rename bin "bin 1.8" rename "bin 1.7" bin goto :END :1.8 cd \ cd %appdata% cd Roaming cd .minecraft rename bin "bin 1.7" rename "bin 1.8" bin goto END :END cd "c:\Users\Stewart\Desktop\" Minecraft.exe exit
3. File > Save As > MCChange.bat (or whatever you want, just remember you need the .bat at the end) and Change Save as Type to All Files
By running the file, you will now have a menu screen asking you to make a selection. Once you've chosen, the file will change the bins then open the Minecraft client.