nah mate, screw all that.
i'm not sure how you're aquiring these mkv files but i would imagine they are from the web and compressed to about 8gig in which case, there is no point wasting money on bluray dics, get yourself some dual layer dvd's and use them, the bluray player will still play them in hd if the file formating system is correct.
Step 1, convert the file
there is a program called mkv2vob - it simnply outstanding and does everything you need. Configure it to convert to m2ts output. Run your mkv file through that.
with the resulting m2ts file, burn it using your burner by placeing it into a bluray compliation, specifically withing the STREAM directory of the disc.
Voila, HD playback.