Oh, good luck!
I have no experience with feeding tubes, but I have a cat who's been on daily subcutaneous fluids for over a year. He's in kidney failure and doesn't respond to the extent that we can ramp down the fluids, but as long as he gets them, he's happy and leads a virtually normal life in most respects.
I'm actually going to introduce an on-topic tie-in: When I give Monty his fluids, I chant the "Sa Ta Na Ma" meditation from Ravi & Ana's Quick Fixes/House Call. (You could sing any simple song instead.) I try to keep it up even if something untoward happens (kitty struggles or fluids leak). It keeps my breathing steady, which keeps me calm, which keeps him calm. It also helps keep my mind from wandering - which is important because if my mind wanders I can give him too much, or it could take too long to notice a problem (like leaking fluid).
Calm is the key. When he was first diagnosed, DH and I tried to do the fluids together, because OBVIOUSLY four hands are better than one ... but he would get impatient, and that would make me nervous, and it just didn't work! Now I do it myself and it goes like clockwork.