If you do a couple soakings with water changes (generally standard procedure for wood, just to get tannins out and get it waterlogged), that should remove pretty much any salt traces. Only thing is you need to get all the wood (or most of it submerged) at once.
If you have 1/2 of it sticking out of the water, it can create a wick effect, and water will creep up and evaporate, leaving the salt behind in that exposed piece.
I've used ocean-collected driftwood in a few tanks, I just do a pretty long soak with frequent water changes, and haven't had a problem. I used a multimeter to test conductivity of the water as a half-assed attempt to try and measure salt content, and the conductivity did decrease a bit over the week with 1-2 daily water changes.
Also tried tasting the wood :P