Hmm... Usually cats dont like to sleep in a box. My cat is indoor and outdoor, and spends some of the day out, then sleeps in my room at night.
To get your cat to like the outdoors, here is some step by step instructions!

1.Take your cat everyday outside ON A LEASH. letting your cat outside on a LEASH makes him think you dont want him to be free outside, will trigger his curiosity, which will then make him want to explore the outdoors.
2. After your letting your cat on a leash,( Or String, or even holding him) You will tell that he will try to struggle on his holder. This is when you should take the holder off of him, and then let him go. He will most likely just stay on your porch for a little, and then run back inside.
3. Keep doing this everyday, until your cat can stay outisde without running in for about 15 minutes. NEVER leave your cat outside for a long time at the beginning unless HE doesnt come in, because he will get really freaked out by beign outside for so long, that he will not like the outdoors, thinking it of a place where he gets scared.
4. Once your cat can stay outside for 15 minutes with you watching, go inside with your cat still out. If you have a screen, leave that closed, but keep the door open. If you dont have a screen, leave the door a little cracked, but not enought for him to come in. Check on him every five minutes. After about ten to fifteen minutes, bring your cat in, EVEN IF HE DOESNT WANT TO. Give him some kind of treat. Now, since you took him away, even if he didnt want to, he will want to go out again! Each day, add about 5 minutes. Keep your cat inside at nights.
5. After about a week, you can let your cat go out for as long as he wants. Let him in anytime he wants, even if it hasnt been 10 minutes. If you leave him out if he wants to come in, He'll think that if he goes out he might never be able to come back in, and therefore not go out.
6. Now, If you want your cat to go out at night Follow this: This is the easiest. Your cat might have already escaped and gone outside by now, since his curiosity made him, because you didnt allow him before. One night, bring your cat to the door. Open it, and then walk away. Try not to let your cat see you watching him. You cat either might be very cautous in going out, or dart out before anyone could grab him. Let him in when he wants to.
7. If you dont want to cat to go out at night, Do not ever try to let him out. If he happens to escape, do not let him back in. If you do this, it will think anytime he goes outside at night, youll let him back in. The next morning, let him in. Do not give him a treat. But pet him, and play with him alot, so he knows being inside at night is much better than being cold outside at night. Lay down, and let him lay with you.
If your still having trouble, pelase email me At:
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Also, i hold a fanmail thingy where people email me eragon questions, (any of the books including 4th, last and final)
I hope your problem will be solved! Good Luck!