Hi Chris,
We don't anticipate releasing Utility Network Data Loading for Sewer in the short term. My suggestion is to use the generic Data Loading Tools Data Loading Tools | ArcGIS Solutions with your input sewer data and your desired output asset package and establish the mapping yourself.
Think of Water Utility Network Data Loading Water Distribution Utility Network Data Loading | ArcGIS Solutions for Water as the Data Loading Tools preconfigured for a common representation of a water distribution system as the source and the most recent water asset package as the target. The documentation includes some additional useful info when working with water datasets, but will highlight concepts that will help you with sewer or other data sets.
So you would use the same tools - Data Loading - just feed your source and target in and establish your own mappings. Yes, you would have to do some extra work, but we've heard from other organizations loading sewer data that once they understand how the Data Loading Tools work it is a quick process to set it up for their specific source and target.
Hope that helps.
Regards,
Howard