Possibly, in some cases. If the couplers are listed separate then you can do it within the config file. In the example below (a gondola) the first two entries are the bogies/trucks and the last two entries are the couplers (front/rear). Otherwise, I think they are part of the car/loco mesh and you would need access to that.
bogey <kuid2:76096:50000:1>
bogey-1 <kuid2:76096:50000:1>
bogey-2 <kuid2:124017:5007:1>
bogey-3 <kuid2:124017:5008:1>
