Good ol DV6. Well, you could, but you basically have take your entire laptop appart and replace your current motherboard with one that has a dedicated GPU soldered on. Of course, your only options are the 7600 and the 8400M. You would also have to replace the cooling assembly and there's a good chance you will damage the CPU when removing it from your old motherboard and cooling assembly if you're not careful. You can find the parts on eBay. Just be aware that there exist the chance you will break one of those delicate parts or ribbons and essentially render your laptop useless after spending $100s of dollars on it.
Have at it