Step 1: Gather Required Materials
1. Small screwdriver, it uses a triangle head but a small enough Philips or Flathead will work with a little pressure.
2. Gameboy cartridge, DONT USE A POKEMON GAME, its a waste :)
3. Razor blade, you can use a dremel, but I dont have one because im poor :/
4. and finally, A USB drive. Can be any size, i used a 2 GB
Step 2: Separate the halves of the USB drive
Step 3: Take the game cartridge apart
Step 4: Start hacking away
The cut part on the back side needs to be a little bigger so you can slide the two halves back together.
After that you can fit the USB snugly inside of the holes.
Step 5: Reassembly
Now all that is left is to reassemble it the opposite way you took it apart and your done :D
Step 6: Extras
Two things you can do is to take the sticker off as i have done, and find a way to make use of the slide mechanism that is on the original USB drive so that yours slides in and out of the game cartridge.