Well, there isn't really much room for error, meaning that once the part snaps in place it's in place and things won't break down, it's just a link. I did it myself and I have warranty... It's also a BMW OEM part, different than installing the UUC shift kit or any other aftermarket brand. Visually it's also not easy to see that the parts are different (standard vs. SSK) unless it's disassembled and placed side to side. They look the same.
If you are having a CPO technician doing it on the side you might as well do it yourself, if he does it you won't have proof that it was done "officially" by BMW which is what you wanted in the first place with the CPO tech, right?