You'd be amazed how easy it is to sneak into the Lost Light with nothing but a set of coordinates in the general neighborhood, a space bridge, and knowledge of where the access hatches are.
... and half a broken sword, and a blowtorch, and magna clamps, and a jury-rigged fire extinguisher jet pack—
The exact tools don't matter. What does matter is that Getaway is on the Lost Light.
He sticks to (what he clearly assumes to be) the lesser-used and lesser-monitored corridors. It's the middle of the night; traffic is minimal. Several times during the multi-mile trek to his destination, he ducks through service shafts, maintenance tunnels, and even a couple of vents. But he navigates the ship, to all appearances successfully undetected.
... Until he reaches the science lab, where he attempts to unlock the door with a tool kit he found in one of the maintenance shafts.