[Discuss-gnuradio] Setting up OOT module to include/extend another OOT Module class

I am trying to extend the gr-osmosdr source block with a PMT message sink to send messages to it during runtime (to say, change the sample rate). I intend to develop this as a part of a differnt OOT module. 

How do I add such dependencies in the CMake list? (I am not very conversant with Cmake)

Is there a good tutorial demonstrating one such example?

Regards,

Anshul