The "Batch Load" function in the Administrator actually calls a command line tool "userload.exe". If the developer can automatically format the PeopleSoft data into the CSV format, you could then call the "userload.exe" to load the CSV file without needing use the Administrator. More information about the userload.exe command line options is included in the Pharos Help files (which you can access by pressing F1 while in the Admin itself).
We usually recommend using the user CSV format rather than direct database calls since the CSV format is fairly consistent between Uniprint versions.
Hope that helps.