Ok, that age isn't as hard as the really young ones - meaning only a few days old. I would definitely get them checked out by a vet, though, especially if you have other cats in your household. You wouldn't want to bring kittens that could possibly have feline leukemia or feline AIDS into a home with other cats - not to mention, fleas, mites, worms, etc.
KMR is a good kitten formula. I would go with the powdered version, because word came through my wildlife rehab that there have been some issues with the canned liquid formula being bad. Use one of the baby bottles you find near the formulas. You'll need to cut an 'X' in the tip of the bottle large enough that just a steady stream comes out when the bottle is squeezed while held upside down. I would start with the bottle now, but leave a small dish of formula where they'll sleep, since they will be able to slowly adjust to solids soon.
Warm up the formula until it's lukewarm (do the wrist test - it shouldn't feel hot or cold on your wrist) and allow them to drink as much as they want at this point. They should be able to tell you when they are full enough. In order to start them sucking on the bottle you may need to push it into their mouth and squeeze a small amount of formula in so that they realize what the bottle is (seriously, would you just trust someone if they just did that to you?

) I would do this 3 times a day now - 8am, noon, 4pm and maybe at an 8pm if they seem a little thin or malnourished right now. They should have a good sized belly on them at the moment.
They should be starting to go to the bathroom on their own, but they still might need some help. Before or after each feeding stimulate their private area with a lukewarm towel/paper towel/cotton ball, just rubbing it lightly like a mom would be cleaning off the kitten. They should still go when that happens.
Health-wise, overall, how do they look? Clear eyes? Alert? Fleas or mites? Clicking noises while breathing? Sniffles? Solid feces? Those are all things you'll need to watch for right now. If they do start having diarrhea due to the change over to the formula, you can mix some plain pedialyte with the formula (1/2 formula/1/2 pedialyte) to keep their electrolytes up.
Once you see them start to drink the formula from the dish, I would start to mix some mushed kitten food in with it (about a tbsp full or so). Once you see them steadily emptying the formula from the dish, I would take away the noon bottle feeding, and then the others as long as they seem to be keeping their weight steady and gaining. I would say that could happen over a 1-3 week period, maybe? However long it is, it should take a little time and adjustment for them. Always watch to make sure that everyone is eating and not just one or two. A kitchen scale would be really helpful right now with them.
I feel like I might be missing some things so here's a link I found just in case:
http://www.feralcat.com/raising.htmlGood luck with them! But I'd definitely hit up a vet and get them checked out before bringing them home!
Melissa