How do you get past the guards on Counterfeit Island?

In the Black Widows Lair

Go along the bottom level until you get to the end. Climb up behind the guard and get above him on the boxes. When you see the female guard (third level) walk over and turn away, jump up and sneak behind her until you get near the chair. Jumping on the springy chair should send you up and left to the locked door. (You have the key card.)

In the Museum (daytime)

Take the Underground Tour, and when you return, you can apply for a job.

In the Museum (night)

Slip past the Security Room while the guard isn't looking, and hide behind the statues to avoid the lasers as you go to the right.