Well it's not as painful as you may think.
//name of your blendshape node
string $blendShapeNode = "blendShape1";
//the new name you want for attribute
string $attributeName = "blend0";
//This give you all the blendshapes and which weight slot they are going into
//Not necessary to run, but if you have more than one blendshape attribute, it's helpful to know which one you want to update
string $name[] = `aliasAttr -q $blendShapeNode`;
//This will update the name of the blenshape for the first weight[0] attribute
aliasAttr $attributeName ($blendShapeNode + ".weight[0]");
You may need to refresh your attribute editor to see the change, but it should go from something like this:
to something like this: