My cats never minded the carrier. I leave it out all the time under a table with the door open or removed. I have a comfy blanket in there and it's just another bed to them eventually. I always started out with the two halves folded together then eventually put the top on properly. Try to expose the spooky kitty to the box slowly by adding food or treats and go from there. Is this cat sociable with the others? Would she go in a carrier the other cats have been in?

Also usually the only worms you can actually see are tapeworms. Most over the counter wormers won't kill them. Your vet will give either a single Cestex pill or an injection. My 2 fuzzbutts got a general worming over a month and a half ago but I had to take them both back yesterday because I found tapeworm segmets on Havoc's rear end.

Good luck!