Yes you can stick frags to rock using superglue gel. Regular superglue is normally too runny. Once dry the superglue is water proof and non-toxic but do the work over a bucket of tank water and after the few required seconds to bond put the frag in the bucket to cure and rinse before returning to the tank.
You don't glue the rocks together, just the hard corals to a rock to keep it in place. The rocks are either cable tied, pinned with acrylic rods, balanced or cemented in place with milliput. Milliputted rocks can be prized apart but generally you don't want to move an established tank.