Microsolder and reballing are two different things. The chip is a BGA chip that he would need the proper stencil for, as well as a reflow machine to remove and reattach the chip.
It's a matter of the bios and everything being able to handle it as well, especially when it comes to trying to switch a graphics chip, it's not just that easy. Companies don't add extra's into a board if they aren't needed. The other problem is trying to get a chip to replace it with. They are sometimes not the exact chips as a desktop model. Things as simple as power pins being in a different spot can make it not work. Unless you can verify that that the 1000 or so balls are EXACTLY the same as a normal chip, you're SOL. Laptop chips are normally different to begin with from desktop chips. You shouldn't have bought a 2 year old laptop if you didn't want a slow laptop.
This is all providing that your friend has the proper equipment and knows how to reball, just not solder.