"Easy" or "Hard" Is VERY subjective. What may prove "Easy " for me may prove excruciatingly difficult for someone else.
You can fit it to the manifold. It can be done, I would consider it a "moderate" mod as there is some fitting and mockup required to get the thing in a position you can use it.
Why are you considering it, are you experiencing boost creep with your present setup? Porting the exhaust housing on the turbo may prove easier and solve your problem or lessen it to a great extent. Eventually you have to go external, but for most daily drive streeters, you can live with the integral wastegates on many of the available turbos.
Well I'm pretty mechcanily inclined and have all materails needed and I'm looking at running 15 psi max on a T3. I wanting to use one because my friend blow out his rings on his 280zxt at 9 psi because the stock waste gate didn't open and I've got a $3000 engine and don't need any trouble.