We have all had or seen cats which detest cat carriers, and who will do anything to stay out of them. There are some easier methods to get a cat into a carrier, and there are ways to get a cat to enjoy, or at least tolerate, a carrier.
If, at the moment, you do not have time for training and just need to get your cat in a carrier in the next few minutes, try turning the carrier on end so the door is on the top. Hold your cat on his upper body underneath his front legs, so he is more or less hanging in the air. Now try placing your cat in the carrier back feet first. There are also carriers made which open from the top as well as the sides.
If you are looking ahead to a time when you will need to have your cat go into a carrier, try the following:
Start placing absolutely wonderful treats just inside the carrier. If the cat is too afraid to get that close to the carrier, place the treats as close to the carrier as you can without making the cat afraid. You can do this several times a day. Start using a word such as 'inside' as you place the treats in the carrier. Let the cat eat the treats and then leave on his own. Slowly move the treats farther and farther into the carrier so now your cat will go into the carrier to get the treat. Do not close the door on the cat. Now you can start feeding his regular meals in the carrier. Continue to use the word 'inside' or whatever word you choose, when you put the food in the carrier. He will now be associating the carrier and the word and action of going 'inside' with good things happening. When he is comfortable going in and out of the carrier, start shutting the door for very short periods of time (seconds) and then longer and longer periods so being enclosed in the carrier becomes commonplace. Also put a soft blanket or towel in the carrier to make it more hospitable. Now when you need him to go in the carrier, he will probably do so willingly.
An additional aid can be found in the product called 'Feliway,' which contains pheromones like those normally found on a cat's face and chin. Pheromones are chemicals which are used to communicate with other members of the same species. You may notice your cat rubs her face and chin on vertical surfaces. She is leaving a scent there which contains these pheromones. The pheromones from the face have a calming effect on other cats. When Feliway is sprayed into a cat carrier 30 minutes before putting the cat inside, it can have a calming effect on the cat.