It really depends! Some strategies I used: - Get to be friend with them, chit-chat, so that they allow you in - Cut the middle-man, just step over them, talk to the boss - Don't do fair play. Just lie, or trick them to get what you want.
These all seem underhanded and likely to create more problems and corporate culture issues
If you're at the point where these are options worth considering, then chances are the corporate culture has already gone to shit. The ideal solution in such a scenario would be to find a new job, but not all of us are spherical cows in frictionless regions of spacetime.