HI, i just put a wood stove in my portacabin, steel walls and wood and vinal roof.
this is the wood stove, a small 5Kw
you must use an insulated chimney for going through the roof or any flammable material.
The hole is cut 2 inches larger than the pipe and is sealed with a silicone boot, this is a dectight flashing. all this stuff can be bought from
http://www.stovesonline.co.uk
The panel behind the stove is a 20mm thick fire shield with a 4 hour rated burn time, this is fixed onto a 25mm fireproof frame and is the packed with vermiculite, the board is very expensive about 130 for an 8X4 sheet but is used for shielding kilns. figure on paying aprox 1.5 times the cost of the stove for the flue system and dont forget to put a rain cowl on the outside, if you are going shorter than the 600mm outside then do fit a spark guard, the site i gave has a page for building regs so have a read of these.
do fit an air vent, you would be surprised how quickly a wood stove can eat up the air in a room and co alarms are now so cheap you may as well get one.
have fun, they are great and i now have 3 and no central heating. and of course you can cook on them too
Dave