When you say "fixed dock" I assume you mean on pilings, not floating? And which side does the current and problematic wind come from?
Actually, you can take a lesson from the "docking contest" videos on YouTube. What you don't want to do is back in too slow as that will simply give the wind and/or current that much more time to shove you out of alignment. Of course you don't want to back in so fast that you run the risk of damage if you misjudge something or a transmission craps out on you.
If you have a crew I suppose they could walk you back into the sip by pushing the boat off the downwind/downcurrent piling as you back in and control the position of the stern with differential thrust.
But based on the mental image I have of your setup I guess I'd do what you probably already do and that is get the boat as far upwind/upcurrent as possible as I started backing into the slip. I've found that backing a twin is really easy when it comes to controling the boat's direction since you're actually "steering" (with differential thrust) the same end that's going "forward." As opposed to going forward bow-first but what you're actually moving from side to side is the other end of the boat.
So the problem going backwards in a cross-wind or current is controlling the bow. The stern will go exactly where you want it to go.
Once the boat was aligned with the upwind side of the slip I would probably initially use the upwind engine to back and fill with (similar to the single-engine boat in the video) to keep the boat as much upwind in the slip as possbible and use the downwind engine only when needed to push forward with when necessary to try to pivot the boat and move the bow upwind if it's getting too close to the downwind piling.
I would also be tempted to start out with the boat diagonally positioned out front of the upwind or upcurrent piling so that the bow was upstream/upwind of the piling. As you back in the bow will start to move downstream/downwind but by starting out with it "too far" upstream this will give you a bit more time to get the boat back into the slip before the bow gets too far downstream and comes up against the downstream piling. How much off-angle you position the boat will depend on the speed of the current and/or the strength of the wind.
I can see how everything I said would work, but I can also see how it might not work. So it's probably not much of an answer.
Actually I'd probably put fenders (that won't move) on everything I'd be likely to hit and just slide the boat in on those
-- Edited by Marin at 21:15, 2008-10-17