Hi MMfoto
There are two methods of mounting to arcylic, either face mount or back mount., Cold mounting is the only way for cibachrome,
One method is to use a clear silicone that adheres the print to the plexi, as the print and plexi go through the cold rollers the silicone is pressed or squeezed out as it travels through the mounter, much like spreading a bead of emulsion on paper.
This method is sometimes preferred as the silicone catches any dust and travels the dust through the mount and eventually out.
Another method is high grade clear adhesive which I believe Ilford, Mactac, Drytac and others have their variation.
This method is generally for face mounting the cibachrome to the back of the clear plexi.

Be warned , both methods require a spotless environment and a good technician. Most large commercial labs do both methods, but you should know that the lab takes no responsibility on damage or spots within the mount therefore you should be very aware of who is doing the job.

When done properly the results are spectacular.

I would be very interested as well in thoughts on alluminum mounting techniques, as I have a large personal project that I want to mount to aluminum.