First thing, superglue gel only works well on hard corals like sps corals, the stony skeleton of euphyllias etc. and on the bottom of mats like GSP. It does not work well at all on xenia, leathers etc.
Now when gluing the frags you want to take the rock out of the water, dry it off with a towel. dry off the bottom of the frag where you are gluing it. Squeeze a glob of glue on the rock and on the frag. Stick em together and hold for about 10 seconds or so. I then stick it under water while still holding the frag and rock together and a little skin forms of the glue. I continue to hold for about 20 seconds or whenever I get bored or tired. Stick the frag and rock in a spot that doesn't have to much current to let it harden completely for a few hours. Then stick the rock where you want.