I don't have a particular reference to offer but I can imagine a couple of ways of doing this.
I would probably estimate utilities for each country separately, assuming you have enough sample size to do so. If not, and this will be more difficult, I would field the survey as if each country were separate then bring the countries into a single data file where I coded the brand and price variables to be country-specific. I'd probably add county as a covariate and then run the analysis on this larger data matrix. This will allow more stability for the utility estimates of your non-price, non-brand attributes, assuming preferences for them don't differ a lot by country.
Like I say, this will be more work because you have to combine all the country's data files into one and then code the country-specific brand and price attributes; then you pull that larger design into CBC/HB to analyze. I would probably analyze this as a separate model per country if my sample size allowed.