I saw someone on the web that managed to get their little stop down button on the back of the lens to stay in by using something called Blu Tack, a removable adhesive strip. I just jammed mine as I don't see using it on any other body than the one that I have.
A word of caution on the adapters. There are two kinds. One has a flange and will NOT focus to infinity. The other one is recessed and will allow infinity focus. If you're going this route, save yourself a lot of grief and buy the Pentax factory adapters. They are a little more costly, but they are made well out of good materials. I bought one of those cheap Chinese ones on ebay and it has been more trouble than it's worth. It was too big and I had to file the diameter down to get it into the recessed part of the lens mount so it would fit flush, and it was also too thick and would not allow infinity focus. Had to use a flat file to get the thickness down too. Too much trouble for a little cost savings.
If you don't modify the pin on the back of the lens to stay down on a camera that doesn't have the switch, make sure you do before mounting it. The pin can snag into the recess where the lens mount screws are on the camera, and you may not be able to get the lens off after that w/o some major aggravation, if at all.
