I have written to the ONS navigation product experts to provide you with information on your questions.
Judging from your interaction with John on the CRM system, you may have already answered several of your own questions, but just in case, I thought that I would give you some hints:
Your project should use at least two user modules: I2CHW for communication and LaserNAV to implement the tracking engine. There is a large amount of reference material about how to use these user modules available right at your fingertips in PSoC Designer in the form of user module datasheets. To access them, simply right-click on the user module that you want to learn how to use in either the Workspace Explorer or User Module Catalog window, and select one of the view options in the 'Datasheet' drop-down menu.
Contained in these datasheets, there is a description of the APIs that the user module makes available to you, and some example code which shows how it is used. I recommend using the example code in the LaserNAV and I2CHW user module datasheets as a starting point, and reading through the list of API descriptions to learn how to combine, use, and modify that example code to build a project which meets your requirements.
For example, the LaserNAV_fReadXYCounts(&XYData) function will update the XYData array with the current movement information from the sensor.
Anyway, again, it seems like you may have figured a lot of this out on your own. If you have any additional concerns, John and I can answer them most effectively through the CRM system.