HELP! Need to catch a wild cat.

We are in the process of moving across town. 5 years back, a wild cat had kittens under the house. Only 1 survived. But we put food out for her and she adopted the place. You can't pet her or get closer than 2-3 feet away, but it's her home & we've gotten attached to her weird ways! :-) . Now it's time to move and we have to figure some way to catch her to bring her over here. My son already made a big safe "cat cage" at the new place to acclimate her a few days so she will stay here.
When she was about 6 months old, I caught her to go to the vets to get spayed & shots. It was a nightmare! You can't get close enough to grab her, so I got a big fishing net with a handle. Stood about 3 feet away and put it over her while she was eating. She totally lost it! Tore her mouth all up and was fighting it so hard she had cuts all over her before I could get her in the cat carrier. Then she fought that so hard she ripped her claws half out. It took her months to get over that & I swore never again.
What I would like to find is something to put in milk or her food that would "knock her out"! So when she woke up she would be safely in the cat cage without all the trauma. It has to be safe though. Does anybody have ANY ideas? I was up most of the night last night worrying about what I'm going to do about her.