First, I agree with Fath2o that if you will often adjust, his method is better.
I also agree with him about the bungees for pedal control - I hate "pedal flop" - the bungees keep everything in place. One less thing to think about when you are getting pounded in the rough.
Anyway, before and/or after going thru the cleat, I wrap it once or so on the studs (machine screws) that project out from the pedal (used to attach the cleat) - then it will not slip at all. If you look at the pics I have at the picasaweb link above (done on my think legend), you can see what I mean. I used a different micro-cleat on my spark, because I had them, but I actually like the ones shown on my legend a bit better. (the clamcleats CL214 and CL213)
the white plastic bushing thru the pedal is just some plastic pieces I had laying around; I recommend some kind of plastic or rubber bushing the keep the line from chafing, although I have never had any issues. Just look for some piece of plastic that will fit thru the pedal hole, then drill it slightly larger than the line, the file the inside edges smooth, then glue it into the hole. As I look at your ski pic, I think you could probably just re-use the black ones that are already there?
the gray tape is stair tread non-slip stuff, likely at your hardware store. If you use pan-head machine screws (going thru the pedal front to mount the cleat on the back) the wont project much and/or you can add some this closed cell foam between the pedal and the nonslip tread to even it all out.