Is there a way to replace specific classic spell icons with customized ones?

[Darternicus]

Hello, I am looking for a way to replace some classic spell icons for specific spells with some customized ones I want to make. I imagine it has something to do with replacing specific files, and editing existing file for each spell.
For example, many of the Enchanter spells that have the same spell icon of a head silhouette with a white brain inside. So below is a customized version of the spell icon I want to use for the Mem Blur line of spells, and the original one for comparison.
I really like the look of the classic icons and just want to make a few changes. I have no interest in changing my icons to another set. Can anyone please provide a solution?

Enchanter Mind Spell Icon.jpg Mem Blur Line - Customized.jpg