Research methodologies are usually independent of your area. Often, the application of some methods and the examples used to describe them differ depending on the area. For example, empirical research is a methodology that can be applied whether you do research in CS, psychology, or physics. This methodology teaches you how to conduct experiments that are sound (by minimizing different threats to validity) and how to analyze the data in a statistical way (e.g., when to use which statistical test to accept a certain research hypothesis).
In medicine, you might conduct experiments to analyze the effects of some drugs whereas is CS, you would do some performance experiments to analyze the effects of some optimizations. The methods used in both areas are the same, the application might differ largely though.
Hence, it would not harm to study a text book from psychology / statistics, because the tools you learn there are also valuable for CS (e.g., knowing the difference between qualitative and quantitative research or descriptive and analytic). Furthermore, there is no CS-methodology (at least I am not aware of).