Out Door Cat

I always wanted a cat, but I'm allergic. So,  we have a multi-function dog. Then, a cat adopted us. It is happy being out doors, where the non-rolling-in-own-dander makes it no problem for me to be with and he's a little hunter, so I'm happy to have him around. Problem though is there's no in door spot for him. Not even a place I could not go- we have a cat-eating-dog. So...I'm thinking how do I make an out-door place for him to stay in the cold weather without freezing to death? Do I just cover a basement window (the one with the drier vent) and leave a cat-sized hole? How do I tell him: here's a good home. Will he go for a place on the ground? I don't want to build a place for OTHER critters.

Also, is there a way to get the dog to stop wanting to eat the cat, but still wanting to eat the ground hogs?

Thanks!

How do I tell him: here's a good home. Will he go for a place on the ground?  

Not hard to lure him to a spot with a dish of food.  After a couple of times, he should learn.
Don't forget a water dish.

Most cats prefer to be elevated off of the ground.  Warm and cozy is what they usually look for at bed/nap time.  Not too exposed, as they most often prefer to sleep in a safe, semi-hidden, private spot.

I hear you about cat allergies. It is doubtful you will have much luck getting a dog with cat-eating tendencies to change his/her ways.

Here is a simple but effective cat shelter:
Simple Cat Shelter Design  Based on plans by the CSM Stray Foundation



Thee are even more ideas here:
Google image search for "outdoor cat shelter"

I think you've found an idea solution with the basement window. Leave a dish of food and water near there. In the winter he will be especially glad of the heat from the dryer.