I tried to figure out the same thing when I repainted mine with SEM. Ultimately, I just taped off the lock and that worked perfectly.

 

I may have to go down the same path. I'm guessing that an extremely thin 'shim' (akin to a valve gauge) needs to slide into the tiny gap between the housing and the lock cylinder to gain access to the hidden spring-tab that's keeping the whole cylinder in place. Frustratingly, my inner brute just wants to tackle it with a 1/2" drill bit!