Allen
This is what I do and you will get several ways of doing this.
1. Glue down the cork on the road bed. I use white glue or carpenters glue but caulk spread rel thin works too.
2. After glue has dried I use a sanding block and sand the cork to take off the high spots.
3. I paint the cork with a color that is close to the ballast color.
4. Glue the track down. Same as the cork. Test the track and add feeder wires.
5. Spread ballast, Mist with wet water and glue.
This has worked great for my modules and some are 7 years old. My home layout will be hand laid track.
Pete