I had a similar situation last February, and succeeded.
I started by putting cat food out in a bowl every other night. I put it on the side of the street, at the edge of my property at first. Then every time I filled it, I moved the bowl closer to my front door.
Some raccoons, and even a groundhog would also come eat the cat food every now and then, watch out for other animals.
If I ever saw the cat eating, I would open my door and watch him without doing anything. After a few months, the cat was eating at my front door steps and was pretty friendly. My girlfriend let the cat inside one day, and we let him settle before finding who the real owner was.
I started with it at the end of my driveway and parked elsewhere, then moved the bowl up my driveway, then through the grass towards my front door.
It took a few days, maybe a week before the cat started eating from my bowl, I would try and put it out in as visually obvious of a spot as possible to start.
Also if it happens to rain, dump / replace the food