I think you will probably want a Zobel on the Eminence midwoofer, but for the tweeter horn, a series/parallel L-Pad arrangement that attenuates 10dB would be great for double duty - attenuator and damper. Give that a go and check your measurements to see where you're at. If the L-pad doesn't damp the circuit enough, try some different values and maybe even go with Jeff's suggestion of a tank circuit (notch filter) which will act as a resonating damper.