Congratulations (I think?)! This is a great opportunity for you to have a real impact on the direction of your company (or it could be a spectacular failure, which wouldn't be so good)!
There is no certification required to lead this type of effort, so have at it! If you choose to conduct a formal SCAMPI appraisal you will need to engage a SCAMPI Lead Appraiser.
However . . . .
This type of effort would be more successful if you had at least the basic "Introduction to CMMI" training class, and if possible, the "Intermediate Concepts of CMMI" course as well.
The CMMI is a complex set of interdependent practices, and even though I've taught the "Intro" class over 40 times, I still learn new things every time.
"The Book" won't tell you anything about how to successfully lead a project like this though - it will merely give you a view into what other successful companies have done with their process (i.e.; "best practices").