I bought a bait-threading needle for a couple of bucks. It's about the diameter of perhaps a 5/0 hook, and fits perfectly inside the plastic tubes i have. The head of the needle is smashed flat, so you can jam the plastic tube over the head about 1/4" and it doesn't budge. Once done with the tie, just cut off the distorted section of the tubing with a razor blade. You might choose to leave a little of the distorted section on there to help when pushing large hook eyes into the tubing. You'll want a beefy vice (like a Regal) to clamp hard onto the needle, or you could use a workshop vice.
Some day i'll buy the attachment thing, or the vice designed just for tubes, but until then, i'm tying 'em in plastic for about $2.