Fitting nose rings on chooks

We have had dreadful trouble with our three ladies.  As they were sorting out their pecking order they got into the habit of pulling out each others feathers.  The heat in the summer didn't help, even though they had the run of the garden on most days.  Since it has been getting quite serious I recently bought some of those nose rings that stops them being able to pull out feathers.

However, I have no idea how to fit them and after trying (and stressing out the one concerned) I gave up until I could get some advice.  My wife held Paxo in a towel whilst I gently froced her beak open and tried to fit the clip over but Pax kept twisting her head around and I was afraid that she might break her neck.

Does anyone have any tips?

I had to do this too a few months ago. It took 3 goes and seemed sooo barbaric but it did do the trick.
Try having a really good look at her face first and notice exactly where her nostrils are - don't mistake them for markings at the top of the beak.
Your wife will have to hold the hen in the towel quite firmly - my son held mine and put her on her back so that her head was on his chest and she couldn't move it too much with the towel high up round her neck.
Try to do it slowly and calmly but confidently so that you get it in first time.
Mine didn't like it at first and shook her head but within 5 minutes had forgotton about it and could eat and drink normally. Only thing I noticed was that she couldn't peck at cabbage as well or at very small bits of food on the ground.
The beak bit stayed on for about 6 weeks and then came out itself. By then the hen's habits were changed and she's never been as bad at pecking the others since but she's still the most agressive girlie in the flock.
Good luck