Just a heads up. C1Pro does not have a plugin architecture but the "edit with" provides an alternative workflow.
Looks like you can call the individual DXO-NIK plugins from "edit with" and they work. By using "edit with" and "open with" you can choose to maintain the individual steps or just run them on top of the initial "edit with".
Not fully tested but thought others might want to take a look as well :-)
Ian