I rooted using inxane's recovery, flashed his kernel and JIT. I believe you need to do the former before you can flash JIT.
Installing the custom recovery is important because I think it's the only way to install the zip from your sd card.
All of the information on how to do this can be found on the forum mentioned above.
However, you should know that in my opinion, having JIT and root doesn't make that much of a difference..not yet anyway. JIT shows that there are a greater number of "MFLOPS", but I haven't noticed a difference. If having wireless tether is really important to you, you might want to give it a shot-that's the only benefit I see in doing it right now. Installing apps to the sd card isn't really an option yet, and that's the main reason I wanted to root but I didn't find that out until after I did it.