[folivier]

Know it won't help now but as Tom has suggested to buy a few various fittings especially (don't remember what it's called) a plug so you can either pull off the supply line or cut it and plug it off. That way you can get air to all the other systems.
How hard would it be to remove the brake valve? You could bring it to a mechanic shop and they could probably get the old fitting out for you.
Also check the pedal, on mine it is screwed into the floor and can be easily removed.