1) Me109 engines have auto management so dont have superchargers or mix. They do have WEP or boost. dont run with boost on all the time or they overheat quickly. Only engage boost when about to enter fight or flight. You need to quickly put revs down to zero, engage boost then power up - if you engage boost with any revs then you will grenade the engine quickly.
2) for superchargers and mix-
found usually on US Russian and Japanese.
Watch the boost pressure indicator and it will tell you when to apply superchargers. It is altitude dependant so a good rough rule of thumb is
below 2000m off or stage 1 and
above 2000 stage 2
watch for smoke to know when to lean engines.
full details in this excellent article
http://mission4today.com/index.php?name ... ow&kid=249
hope this helps