HEAD GASKET help needed !!!!!

[Mazda6vicksburg]

Hi everybody, I am new to the Mazda forums world and i hate to start my first thread with this kind of a problem a buddy of mine just encountered. He was driving his 04 Mazda6 with around 150k miles on the clock, its a 4 cyl btw, well maintained, well the water pump locked up and shattered the belt, the radiator busted as well, long story short, the head gasket blew, it is not mixing, but the car is burping air into the expansion tank. I am the one he referred to in doing this job for him (i do heads on 4 and 6 cyl engines quite often, timing belt or non-interference, but never dealt with a timing chain driven cars). Im not scared of this engine, but is there a DIY somewhere for a head gasket replacement or possibly any tips and tricks to look out for. I did my search on these forums as well as googled up and down with no real luck, its either different engine or different generation pops up. Thank you very much for any advice/help, appreciate it in advance!!!
P.S. I am looking to start on it this weekend

 

[GAXIBM]

I would do a compression test to see which cylinder(s) are leaking into the coolant so you know where to look. You could have a cracked head or block. Try looking on U-tube...