Basically do this;
-unbolt stock intake
-unbolt itb's from 20v intake manifold
-bolt T3 adapter to head
-bolt itb's onto adapter upside down
-bolt on your choice of velocity stacks
Things to note;
-use 20v TPS
-the T3 vacuum bungs are in a stupid spot
-use the T3 vacuum ports for vacum, not the throttle body ones
-T3 adapter will need slight modofication if you have a FWD water outlet on your engine
-I suggest cleaning up the inside of the T3 adapter (smooth out the edges at least)
-use 16v injectors and fuel rail
-there will be no form of idle control except for opening the butterflies, or opening a vacuum line
-you might want a vacuum box to connect all the throttles to, then connect that to brake master, fpr etc.
thats a basic rundown, obviously not including ecu, wiring so on.
Im sure there was a much more thorough guide somewhere on here or on twincam.org too...