There are a couple different ways to do it just experiment until you find what works best for you. First you can glue them on with devcon 5 minute but I have found super glue JELL (very important not to get regular) works a lot better, drys instantly, and will not come off. Second, get yourself some clear fingernail polish at the dollar store, CVS, where ever. Next lay the lure on its side with the eye facing up. Pull out the polish brush and a bead should be on the end, then just put a drop of the polish right into the eye socket covering the eye. The fingernail polish will cover the eye and fill the socket sealing the eye to the bait. Wait until it dries on that side the flip over and repeat.
Allen