I typically do use procedures similar to Watershed when I'm delineating stormwater subcatchments. However, in this case, my polygons won't be terrain-dependent. I have to draw them in based on service connections.
So in other words, my procedure would ideally be:
1. Activate the script (the basis or language of which I am requesting in this thread)
2. Create a polygon feature (assume the feature class name is Shapefile_P)
3. Script would prompt me to click on a node (which would be in a points feature class, Shapefile_N)
4. Based on selection, script would read the associated NodeID from Shapefile_N and place this data in a field in Shapefile_P.
5. repeat forever on end
Hopefully that provides a little more clarification on my end goal.