Chosen Solution

simple question. can i do it? if i can, how?

The GPU graphics is built into the motherboard and can not be replaced. According to which motherboard you have, you may be able to upgrade it but the cost is prohibitive.

There are now repair services that will replace the chip in the motherboard with a newer revision of the gpu. Check out Brickfence on eBay. IT MAY BE A 10 YEAR OLD MAC BUT ITS THE LAST TRUE MACBOOK PRO!!!