Good luck!
Our two cats were half year old kittens that lived under our windowsill out back for two weeks.. then we decided to lure them inside with a trail of freezerburned wild alaskan salmon
It was a long journey getting them to trust us, but here we are 13 months later and have two loving cats, both ask for attention and petting (and food, lol), one even actively jumps in my lap to curl up/be groomed/sleep at least three or four times a day. The other is still shy about being held or being a lap cat, but seeks us out to sit next to us and very much enjoys grooming.
Good luck with your alley kitty, we've saved a few others from the impending cold here in MN. The actively human-friendly ones are the most likely to get adopted, so I think yours will have some luck.