In reply to leedale30:
First question - is your purchase the right size for the boot? It a while since I got mine but I believe that they are sized.
I also managed to get mine to fit reasonalbly well on non-yeti style boots...
Lookaing onto the rubber rand of the yeti befor you put it on ... its like a big oval of rubber with an oval hole in teh middle. On the new ones, about one third of the way down is a thin piece of rubber across the hole and then one third down again is a big wide strech of rubber. The thin bit goes (eventually) under the ball of the foot/boot whislt the big wide bit goes under the instep.
My method of getting them on your boots is to put the boot down through the opened yeti and push the toe of teh boot through the hole between the thin rubber and the end of the rand. Push through so that about two inches of boot has gone through.
Grab and pull teh back rand part of the yeti and pull like fury to get it up and around the back of the boot, pulling up past the heel.
Now adjust this back part so he the rand is now sitting down close to the base of the heel.
Now continue to pull the yeti forwards so that the large rubber section falls into the instep part of the boot.
Keep pulling the rest of the yeti to start moving the front rand section up towards the end of the toe part of the boot and then pull it over the toe.
A little bit more jiggling to line it all up.
Yes, a bit awkward to fit but fine when on.
My boots weren't really Yeti compatible (Zamberlan and Sanmarco) but the yeti system still fit quite well even to the point where I had my Yeti's resoled.
Watch out when taking them off - I managed to pull the heel off one of my boots when trying to take teh Yeti off them!
Cheers