All post filters are done in screenspace , chromatic aberration is a post filter. Even if you had access to shader logic the depth buffer is the only useful information to screenspace effects so you still would not be able to do any per object exclusion.
Yes I used internal geometry , but I also used two materials , outer and inner to control the transparencies and blending differently. I used the additive mode on the inner geometry. I also used the metal sliders on full for this effect as it is the only way to boost the reflection strength when using transparency. That is a hack of coarse... but it gave fairly acceptable results.