I don't know if this is the right thread to put this on, but I tweaked the Minecraft Portable tutorial on the Minecraft Wiki to make it truly portable. (The other one made use of a shortcut, which means that if the drive letter changed on the drive when plugged into a new computer the shortcut would break)
NOTE: A USB 3.0 or 3.1 device with less than 64GB is reccomended for this, as too big of a drive will lag and too slow of a drive will lag.
Step 1: Create a folder in the root of the drive called "Minecraft Portable" (Without the quotes :]), and in that folder create two subfolders "bin" and "data".
Step 2 (Optional): Copy the contents of the .minecraft folder (to find it click the windows key and R and type %appdata%) to the "data" folder (make sure to do the contents - there should not be a subfolder called ".minecraft")
Step 3: Download the latest launcher from here and place it into the "bin" folder
Step 4: Create a text file in the "Minecraft Portable" folder and put