IMO it would be smarter to just swap to a 2nd gen 3SGTE, but turbo 5SFE can be done for relatively decent price.

The easiest way is to use the 3SGTE factory turbo manifold, factory turbo, and aftermarket downpipe. The factory intercooler and piping will work as well. You will only need one additional custom pipe that goes from the intercooler to the throttle body. You will have no problem finding people selling their old factory crap for a decent price.

Next you will have to consider engine management. For this system to be effective, you at the very least need to upgrade the fuel injectors, and add a fuel management system such as a s-afc. You will also need some sort of timing control, such as an msd btm. You will also need to upgrade the clutch, and switch to a factory or aftermarket turbo exhaust system. I would also recommend replacing the headgasket with a metal one. Then you will need to pay for some dyno tuning. All this for about 10-12psi of boost.

Again, all this said and done, it makes more sense to just swap the motor. I know, because I have been down that road.