i need to create a list of layers in the geocortex site not the esri map service

High, i would like to create a pick list of the layers within the geocortex site, or have the user highlight two layers for calculating the intersection and acreage of the two layers.  How do i create a dataitem list of the layers in a site, not the esri map service layers but the names and details of the layers in geocortex map site.

J