You are posted in the right forum, this forum specifically for IPP questions/discussions.
As I know Icv prefix is for for internal functions in OpenCv.
ippiOpticalFlowPyrLK is a right functions to calculates optical flow for the set of feature points using the pyramidal Lucas-Kanade algorithm. For more information about parameter for this function refer to,
Also, there is an example to demonstrate usage of this functions.
If you are intent to use IPP functions from your application, OpenCV provides a transparent user interface to the Intel IPP by automatically loading the Intel IPP libraries at runtime. For more information