I rarely use flashers anyway. I either use rear IR inputs or the blaster. BTW if you use the blaster on the MRF-250 you will rarely get RF interference. I have come to believe the interference is carried back into the unit on the flashers like they were antennas. I also found some 3.5mm to the little tiny plug adaptors at an everything $1 store. I think they were origionally made for something on a Nokia phone. I bought 20+ of them and now I am almost out.
What I am getting at is that if you find yourself needing more flashers then just turn on the blaster and hope you do not need to route the IR.