You will have to use a combination of glue sticks, plastic clamps and masking tape to keep the bottom part of the trim down. Wrap the masking tape on the windows and door opening to give it more strength. The top part of the trim can be kept down with binder clips at the window openings.
As you can see the plastic clamps and glue sticks are basically to provide weight to the masking tape for clamping. They are useless without the masking tape because there are no areas to clamp to.
Because this piece of under pressure, it is best to let it dry for 24 hours before removing the clamps. Check your clamps every once in awhile to make sure they haven't slipped out of place or loosened.
