sorry aint got access to it for pics for a while,
proceduraly it can be treated as if you were installing 5mm plywood panels but i'll focus on 2 problem areas
- with ply you would i guess use screws, but with acrylic that would ruin the look, so to initially to support the weight it would we good to have a dead straight and level bit of skirting already down, so it would rest on that whilst u get em ready for fixing.
Whilst waiting for the grout/glue (stixall/everbond etc) to set i got some square contoured cable clips and cut off the sides, so it's contour looked like a 'r' instead of an 'n' iykwim.
i replaced the nail in each with a small screw, and these were great for holding the panels into the plasterboard temporarily.
you may or may not want a grout line, but I experimented a bit and found they were useful, because like tiling, errors in the geometry of the wall forces minor adjustments, the width needed for a cable clip (4mm?) seemed about right, and allows for different colours (grey /black /white silicone etc) to add to the mondrian classic you're about to render
In the corner i used a 6 ft 15x15mm rod of acrylic for the panels to butt up against and the join siliconed over as above.
last thing -cutting holes- get an adjustable compass style attachment for a battery operated drill. I cant remember what it's called but it's a drill bit going through a sliding ruler where 2 sharp points are fixed with an allen key, these spin round and cut your holes the easiest.
b./