I have satinettes and I trained mine since they were babies. When they got older I just starve them for a little while and they trap like champs when they're hungry. This is just how I do it and it works really well for me. Not sure what anyone else does for their droppers.
Trap train them with your homers and keep them in the same loft. Then on race day, have your droppers in a crate beside you and don't let them eat before you bring them outside. Mine go right in if they are hungry.
I trim there flights so they can't fly very far, that way they can only fly a little, DON'T trim to much or they wont be able to fly to get water (If your water is raised in your loft like mine is) They work great though