You can try asking at the check in counters at ORD or at the transfer counter at HND if they can check you in to HND-MNL, and manually add the flight to your bag tags. Someone would have to go find your bags and put on new tags so if they don't have the time or manpower to spare they might not be able to (or want to). But JL seems more amenable to this sort of thing than many other airlines, and worst case they just say no.