Depends on how good are you with soldering iron. If you're decent, you can get the chip and do it yourself. But if you're the kind that can accidentally set the desk on fire just by touching the iron, pay someone to do it.
OBEY is easy to install. But it may not work with Turbo Everdrive. If you plan to get the chip and TED, make sure the 5v wire is tapped onto 7805 regulator chip and not elsewhere for best stability.
There's also the old 8P2T switch, no power needed but it's hard to find these switch these day. I used to be able to see them for under $5 a pop but now day it's about $25 so it's actually more expensive than the chip mod.