I've done it in the past using a stiff bristled tooth brush and slightly thinned paint, but as Nino and Gav have said the spray gun is the go as it gives much more authentic results.

I used the spray can webbing on my Zaccaria Universe i restored about seven years ago, though i did it ONLY after a lot of experimenting first before i went anywhere near the cabinet!! I found that if i hit the spray nozzle with short, sharp jabs with the heel of my hand it allowed the webbing to come out a lot finer.

Practice first on cardboard etc first though if you try the spray can webbing!!