What I did with my bubble (RIP) and torch, was to use some of that underwater aquarium epoxy and basically "welded" the stalk of the coral to my rock. I put a blob of epoxy on the rock, stuck the stalk straight into it, then added more epoxy around the base of it to keep it stable side to side. Hard to describe... here's a picture...
I'm not overly happy with how much I goobered on there, but the torch was more top heavy than I realized and you don't have a lot of time before the epoxy sets up hard as a rock on you. (I'm also not thrilled that the epoxy that I bought from my LFS
dried white, when the person there said it dried grey! Grrrrr.... Oh well... it's already starting to be covered in coralline algae, so I guess eventually it'll blend in better.)
I "prekneaded" little chunks of the epoxy (you knead it to activate it) and set them nearby, then quickly did all the work underwater. It's not difficult, you just have to work fast and delicately.
I've used super glue gel (cyanoacrylic) underwater for zoanthids, and that works well. But it seems like frogspawn and hammers are too top heavy for superglue to really work - unless you have a good pocket already in your rock that the stalks can go in to, and the super glue will just keep them in the pocket.
PS... The "AquaStik" on this page is what I've found works best. And it dries grey!