Yes - It is done by creating a Repeat Region Relation where a new parameter is set equal to the desired formula and then that parameter is used as a Repeat Region column.
Example relation: newmass = asm_mbr_pro_mp_mass * 1000 (the "." separators are replaced with "_" separators)
Example Repeat region entry: &rpt.rel.newmass
The "newmass" parameter is automatically created when the Repeat Region relation is created; it isn't required to create this as a model parameter. It is only visible from the Repeat Region. The 'type' of the "newmass" parameter is automatic.
Any parameter that is created relative to a Repeat Region is used in the table with the "rpt.rel." prefix.