You'll need a 15 thou (0.4mm) feeler gauge, a flat head screwdriver, 10mm ring spanner, a flat surface and enough tools to take the rocker cover off.

It's also done when the engine is cold.
Take the cover off, only do cylinders where you are sure the valves are completely closed.
place feeler gauge between the rocker and the valve stem, place ring spanner on 10mm locknut and flat screwdriver in the slot on the top.
Crack the locknut with one hand and set the gap by turning the screwdriver, tighten the locknut and check.
Repeat as necessary.

Repeat that on all the valves you know are closed, then put the truck in top gear and push it to turn the engine over. When it's closed the valves that were previously open, you can do those too.

My 4BD1T is usually a lot smoother and quieter when the valve clearances are done.

Which turbo did you replace and whereabouts are you?
I'm looking for parts for the japanese IHI-RHB6 turbo.