To the best of my knowledge full size walkways are usually non slip paint, so I use paint also.... easy to reproduce! best method I have found is use higher airbrush pressure and less paint mixed a little thicker then apply paint in light coats until desired effect build up is achieved. You will end up with a dry orange peel looking effect, sort of oppisite of what you want when painting a model just remember to experiment with varing degrees of air pressure until paint is going on near dry....
heres a couple of pics I just took of the walkways on my CF-18 applied using this method. Sorry about pic quality as flash tends to washout the detail but pic without the camera flash on you can see the texture much better and I think you can get the idea.