Dear Random,
Maybe I should have included this, but I assumed we are talking about someone who is seriously ill. (Oxygen around 90. High fever.) If the nebulizer would be ineffective, the next step would be to go to the hospital. I got advice from a frum doctor. In that instance, he also said that if I could not get it on with a spoon, I should turn it on regular, instead of calling hatzolah or going to the ER.
I also shold add, that when using a shabbos clock, have it stay on for at least an hour at a time. In case it has to be redone, you will have enough time to do it twice.