It sounds like you have a very young veiled. You can dust the fruit flies in a zip lock bag...just shake them up. You should have your little guy in a rubbermaid tub with some greenery and just dump the flies in. I hope you have the ones that can't fly. He should also be eating small crickets.
fruit flies can be semi gut loaded with a horrable concoction of bee pollen, powdered milk, and powdered kelp. You add alittle water and have the cotton ball suck it up. Its really really sticky-n-gross but it works.
Use a 2nd cup, dump about a half dollar sized amount of flies in, recap both cups. Put dust in with flies to be fed, gently mix, then dump in enclosure.