I've got a set and have yet to use them in anger. My first reaction was, that's quite neat, reasonably robust, nicely finished, good knobs. Then I came to put them on my kity and thought the same as you - not enough space to use them. And I certainly don't want to have to remove the whole cutter block!
But the problem was with me, I had the table too high. By retracting the infeed table to give max depth of cut I had plenty of room to work on the head itself. I guess it is possible that a small machine is too small to use these, but they will fit on my 637 with the outfeed table up and the infeed maxed back.
So I suggest you try that, get the jigs on the blade as it is now (assuming it is currently set OK) and take a reading. Record it in the lid of the box for future reference.
There are instructions, but they are a bit sketchy.
As I say, I've not actually used them to set blades yet, just had a little play.
Cheers
Steve