You dont need the error code eliminator.
By relays I mean a relay, its a complete overlay harness that gives a dedicated B+ to the ballasts instead of throught he oem circuits.
you can buy the harness drawn above from basically any hid vendor (check out xenon depot in our venders section), only difference is you plug pin 87 into the ballast and not run it straight to the bulb. Still a VERY simple install. If its not something you have done before you it may look MUCH worse than it is, so long as you know how the birds and the bees work so you know how the males plug into the females its very straight forward...
I like to pull the front bumper cover off, I have my headlamp ballasts and relays mounted to the top of the crash bar. That said the first night I installed them I didnt take anything apart and just ran the harness where I could... I was pressed for time that night