I need to catch my extremely skittish, hand-shy cat for flea treatment.

Butter is a roughly 8 year old former semi-feral who we've fed for pretty much all of his life. He began coming inside the house through the dog door and I'm thrilled.

He's doing great hanging out near people and communicating if he needs or wants stuff like treats and fresh water.

But Butter runs if you walk near him or outstretched a hand. (He has bitten someone before as a much younger cat, but it wasn't really his fault, he was just cornered, in pain, and scared.)

What I failed to realize is that, naturally, Butter is absolutely covered in fleas and now our house has an infestation. The house is covered in DE, vacuuming and laundry are constant, all that.

I'm trying to get it under control but it means nothing if the cat's still a fleabag, you know?

I was thinking a potential option might be to just crush some 24 hour Capstar into wet food and feed it to him repeatedly, but I'm wary of giving him so much poison.

I have some Advantage XD that has been given to our indoor-only cats. I'd love to try and get some on him
I need advice for potentially trapping him somehow and giving him the medication. I don't want to do it badly and accidentally hurt him but I need Butter to not have fleas anymore.