"SEO ACCY" refers to a specific fuse, likely within the vehicle's fuse box, that provides power to "Special Equipment Option" accessories. This often includes items like mobile radios for police vehicles or other aftermarket equipment.
I have this slot.
This slot gets no power when the key isn't in the run position.
Trust me I don't doubt your method and I know its sound and proven.
I'm learning so please be patient with me.
The main issue would be testing to make sure that the circuit is not overloaded correct?
Update: Thanks for the "why" question. It led me to do some more research. While theoretically the fuse tap would work it's likely for the radio to overload the circuit. Lesson learned and that came simply from you asking why. I appreciate your response.
Feel free to add any nuggets that you think that might help further.