If you are working with a color print shop, you might ask them how their process learns of job spot colors (coming in with .ps files historically, but like .pdf now). I've often wondered about that, but only wondered, as the need never arose. My print pubs always ended up as B&W.
A key question in this is: does the FM color name survive into the .ps or .pdf? If it's a print color library name, such as Pantone® in older FM versions that included that library, having the name survive into the print shop deliverable might suffice.
If this name path works, it may or may not require that the FM color be defined as "Spot" rather than "Process".