Right click on 'Minecraft.exe' or 'Minecraft.jar' (the launcher) and press "Create
Right click on the new shortcut that gets generated and press "Properties".
At the end of the 'Target' bar, add the following:
It should then look like this:
Simply press 'OK' and then run the shortcut, and Minecraft should launch.
Things to keep in mind
In any event that you would need to open '%AppData%', instead use '%ProgramData%'; as you
have set the game to use this folder instead.
If you should ever need to move the actual "Minecraft.exe" file (not shortcut), you will
have to follow these instructions over.
Mac OSX and Linux
Please create a terminal script that launches "Minecraft.jar" with the --workDir
parameter, to a destination that does not contain special characters in it.
open ~/unsafe/path/to/Minecraft.jar --workDir /safe/path