A layer selection menu allows you to select any layer in the composition as an input to the parameter:
Layer selection menu
Select the desired layer through the first popup menu:
Layers in the composition are available in the menu
Once a layer has been assigned, the parameter reflects your choice in the inspector:
A layer has been assigned
Please note that content for the selected layer is only available in sections that overlap:
Layers with non-overlapping sections
No content is supplied to the plug-in for any sections where the layers do not overlap.