Is this possible with the blender node comp system?
What i am want to do it blend to images together, but instead of an even blending im wanting it so that i can blend the middle of the image and not the out sides of each image, but have a smooth transition to each side.
sure, use an AlphaOver node that has its Fac: fed by a horizontal gradient from black to white (not just a number, but an image); where it is black the image from the top input socket will be used; where white the bottom input image will be used. See the alphaover node toucan examples for the idea.