The Clicker.... or should that be Clickr... 
I've read a few posts on flickr where people have tried using one of these plastic clickers to count sprocket holes but it has failed. Once you know how to make one, they work really well, so I thought it would be worthwhile documenting it properly here. The key is to ensure the clicker plastic only goes through the sprocket hole by a small amount, and it seems to work best with the clicker very close to where the film comes out of the canister.
It was time to reload my matchbox pinhole for the summer, so I took the opertunity to take some snaps of the process.....
First tip: Carefully wind back most of the film leader into the canister (don't go too far!!!) - this gives you extra film to test the operation of the clicker.
Note that the plastic ( I use a small bit of very curved plastic cut from a document binder) only protudes through the sprocket hole very slightly
Before reloading, genly pull the film out a couple of sprocket holes. The clicker should ride on the back of the film smoothly and make a click as it drops into the sprocket holes. It does? Good! It doesn't? Remove the tape, wind the film back into the canister again try repositioning the clicker slightly.
Snip the leader off as square as you can. Now splice the film with tape. Make sure everything is square....
...both sides. Trim off all excess tape carefully
Wind some film through to tighten the canister against the box, hold it there and wind a couple more clicks to make sure the clicker is still working.
Now tape it. Tape it good. Tape it reaaal good. 
Note the end of the clicker plastic is left visible. When the film is finished, grab this with some pliers and pull the clicker right out. Now you can safely wind the film back to the original canister.
i used your (very concise) directions a few months ago to make my first matchbox camera, and the clickr worked liked a charm!