I installed Dynamat & new carpet last year. I used 3M Adhesive for Carpet & Trim. Worked well glueing the carpet to the metal and also to the foil Dynamat material.
I didnt glue down the 4 pieces for the floor wells(2 front, 2 under the seats). This way you can lift them out, clean them and also ensure no water is under them.
I taped certain pieces (ie. inner rocker wall side pieces) on the top edge along the chrome strips. Then carefully lifted them up and sprayed the adhesive, working my way down to the floors. Used a wallpaper roller to ensure carpet was pressed down with the glue. The top section of these pieces can then be pressed into the chrome strip along the door using a plastic putty knife.
I area that caused a bit of an issue was the back wall of the soft top well. The left side, as it curves around from the soft top handle towards the right side, is not completely even, so take your time glueing this back piece. Tape the piece on the top edge and do a dry fit to ensure it is evenly set. Then start glueing it from the top left side first. I would suggest glueing the left side completly, then the middle section working your way towards the right and finish on the right side. The 3M glue is applied on the carpet back and also on the car metal, so you can stick it and peel it away again if you need to readjust as you install.
When I re-install carpet and Dynamat again this summer as I complete my resto, I will do it the same way, except I may use the Dynamat Pads for the 4 floor sections so that I can lift the Dynamat & carpet out of the wells and clean and ensure no water is hiding under them...
Bob