How can I shield cables from interference?

Sure, should be no problem as far as I can see. I just find the first solution a bit more simple and less wires hanging around.(-:

The idea you mention is a good possibility. You have to solder a bit of wire from the shield to the ground pin of your powerplug which goes into the wall. The end , which goes into your gear, you'll have to leave open. This works only however, if you have a properly grounded line.
Besides, never run pcs in long parallels with your other wires and if you have to cross other wires with your pcs, try to do this at right angles. As set up like this, mostly helps a lot.

Perhaps you should drop our Sean here an e-mail with that question about conductive nylon, because I believe there are certain drawbacks with the normal metal mesh being used. Unfortunately I don't know which. I've been using home brewed pc's with metal mesh with excellent effect by the way, so the drawbacks cannot be all that great, because I've compared mine with expensive aftermarket stuff. About the solder, I'd use normal "audiophile" grade stuff, with quite a bit of silver content. And while you're at it, why not install cyroed hospital grade plugs, they do make a difference.