As of V12 SP4 there is the possibility in PARTproject to export only certain files in PS3 format via catalog context menu command Output -> Generate image data/preview images and then these files to convert into the rfa format via scripting.
In order to filter certain files, in the dialog Export files, under Source, select the option Order Numbers List and choose a CSV file.
Details on this can be found under Section 5.14.1, “ Revit: Create specific rfa files from projects by using a filter ” in eCATALOGsolutions Manual.

