The Hitec HMI programming cable is finally available. AND it is FREE 
Now you can program the 5990 and the other new HSR servos.
Does not work with non HMI servos. also does not allow changes to configuration on older 8498 servos.
where do we purchase?
There is a schematic in the manual of the cable. It is one resistor and a 9 way connector. you will also need a servo cable extension and a battery pack/power supply.
I found some major errors in the Hitec specification above (check is wrong, setting motor position is wrong). Also some commands missing, though probably done on purpose.
Use this until Hitec make corrections.
robosavvy.com/site/Builders/i-Bo … serial.pdf
Software does work OK for 5990 with 1.1 software. On 1.08 software (old 8498) you cannot write the config to the servo EEPROM.