Radiator control is fully automatic on Spit IXs, there is only a pushbutton for testing whilst on the ground, not moddeled in game. I personally think that the IL2 spit overheats to easliy and manual control wopuld be nice. You should be able to run at +12lbs boost for an hour...your lucky if you get 10 mins in game at that setting. This is normal climbing power according to the manual.
The supercharger is indeed automatic and in reality it should come on at a set height and then turn off at a lower height .around 1500 ft lower, this is because its an air pressure operated switch and if a spit was hovering at the engage height it may flicker between on-off. Instead it turns on at say 21000, and turns off at 19500. The actual height depends on the engine fitted, i.e. for the LF, F and HF versions its different.
There is an overide switch to switch to the low gear at any height, but this is not operational in game. if you look on the instrument panel you will see a switch next to the Supercharge light. This says, Automatic/ MS gear. this is the overide switch.
The supercharger is not moddled very well in game as its operation also depends on throttle setting as well as height. Also the WEP/boost is inaccurate with the IL2 version Spit (its correct on the modded SPit XIV available here) as there was no separate control for boost, simply the pilot pushed the throttle further forward (The P51 with the merlin is modlded correctly in this regard as is the new Spit XIV)
I have a copy of RAFs Pilots Notes for the Spit IX and this is where I got the info from. You can get these from
www.crecy.co.uk for a modest fee as well as pilots notes for other aircraft, I use these when flying an FSX Spit IX (the Realair one)