Go On your usb and make two folders named bin and the other data Then in the bin folder put ur minecraft.exe (or minecraft luncher) Then do start and type in the search bar %appdata% and copy .minecraft in to your data folder
Then go out of the data folder and make a Text Document and copy and paste this in

set APPDATA=%CD%data
binminecraft.exe
And then click file>save as and name it minecraft.bat
And your done HAVE FUN!! :D