I recommend you improving your awareness on the concept of Six Sigma. If you check Wikipedia, it says, "The term Six Sigma originated from terminology associated with manufacturing, specifically terms associated with statistical modeling of manufacturing processes. The maturity of a manufacturing process can be described by a sigma rating indicating its yield or the percentage of defect-free products it creates. A six sigma process is one in which 99.99966% of all opportunities to produce some feature of a part are statistically expected to be free of defects ".
In light of above definition, I doubt whether it is possible to implement Six Sigma in "employees confirmation and employees promotion process". However, there other ways to improve these two processes.
As far as performance management is concerned, even without Six Sigma also, you can do whole lot of things. Call me on my mobile if you wish to get more information.
21st March 2015 From India, Bangalore