Curved needles! Just about any fabric store should have curved hand-sewing needles.
A curved needle will help with being able poke the thread through the Cordura and back up through it without going through the liner. You can also usually pull the outer layer and the liner apart somewhat by carefully pinching the fabric on each side and pulling to open a small air gap between them. It's also useful to get a thimble, since pushing a hand needle through Cordura takes some effort.
It's been a long time since I looked at a Chrome, but if I remember right you can separate the liner with velcro around the edge of the main compartment, and then slip your arm inbetween the layers in the flap to tent them apart.