As we know, the adeptus mechanicus is just as susceptible to the lure of chaos as any normal human. Often in novels this is portrayed as an attack by chaos contaminated digital scrap code, in a manner akin to a computer virus.
Still this raises the question, what appeal could the creed of a cosmic entity such as Slaanesh have to a computer cyborg? Presumably, the appeal of the flesh have very little draw to a mechanized entity. But then again, Space Marines are essentially immune to sexual attraction as well but they readily fell too.
Slaanesh isn't only about earthly sensual desires though. His path is ultimately about the quest to achieve unlimited possibilities, complexity, pleasure and perfection in a physical material world. While the adeptus mechanicus does not pursue sexuality, it does often pursue unlimited knowledge, without remorse or limitation.
In common, the creed of Slaanesh appears to dictate the following tenants to its adherents, whether Emperor's Children or Dark Mechanicum:
1. There is no inherent spirituality except as manifested through the material world.
2. The material world has in it a teleological drive to improve and expand, akin to evolution.
3. This drive is experiential and can be expressed through increased knowledge, complexity, experience, or pleasure as a path to greater awareness, development and awakeness.
4. There should be no limitations placed on this drive, as progressing down its path is an unmitigated improvement.
5. The goal of this drive is to achieve infinite possibilities and perfection.