I use Glidden Gripper acrylic primer to glue both cork and foam. Works GREAT, and is very easy to spread with a small roller for large areas. Put it on a little thick.
-Kevin
I did this in several large areas on my layout. I spread the wood glue on the plywood with a fine-tooth tile trowel. Gives a nice even and thin coat of glue. Roll the cork out over the glue, and weigh it down. Use wax paper between any large weights or they'll glue to the cork.
Randy