Quite simple John, wood blocks are the easiest, inside and along the edge of the cabinet you want to attach clean and lightly sand the fibreglass on the inside to remove any contaminated and deglaze, Apply 5 minute epoxy to the area and side of the block contacting the wall and press into place, holding until the epoxy sets. Then you can use screws through the side of the cabinet into the wood block.
You can also just use fibreglass resin and cloth and bond the cabinets directly to the walls (after cleaning surfaces), but then the cabinets cannot be removed.
I am in the process of doing this now. If you go onto YouTube and type in scamp rivetless you will find some information on it.
What I did was I removed all the cabinets, but before I removed them I marked the places where I would like the blocks to go. I pulled back the ensolite and cleaned the area and glued the blocks in place (this is the step I am on now), once that is done I will be covering them with resein and cloth to make the fibreglass, once that is done I will glue the ensolite back in place and I will be done. I did dry fit the cabinets as I had one block in the wrong place.
I used 3/4 plywood cut in strips, for the rounded sections I traced the curves out on the plywood and it seemed to work.