I've said this on another thread, but all of mine, upside down on my lap, back feet against me, and I used the guillotine clippers. They were not thrilled, but they put up with it. One of those "no options" items, "yes, I will clip your toenails, get over it." I would allow a break half way through if the "victim" was getting restless, but for the most part I had no difficulties. I used to finish up with a file to smooth things out, and because I didn't want to chance cutting too short. And being released at the end was reward enough for all of mine!
I want to add, I have had the most success working with animals (mostly horses and dogs) one on one. They do not like feeling ganged up on, which can be a problem if you have an assistant. Yes, sometimes necessary if you need an extra hand for the job, but otherwise I think if the animal trusts you, better to work alone.