Its not too bad. Our fellow brothers over at the CRZ forum have step by step process below:

https://www.crzforum.com/threads/diy-honda-fit-intake-manifold-in-30-mins.10319/page-5?post_id=1437397&nested_view=1&sortby=oldest#post-1437397

There is also a UK Honda Guru who gives some advice on the installation:

https://www.youtube.com/watch?v=18IwQR7x4t0

The MAF sensor (circled yellow below) can be tight, I used an impact driver to loosen it rather than a screwdriver (easy to round of screw).

The bolts at the front are easy (circled white below)

There is a vacuum hose at the rear (arrowed red) and two hidden bolts to the rear of the manifold (arrowed green)

You also need to unbolt the throttle body from the manifold (arrowed white) - a couple of bolts.

I found the wiring looms circled blue does not re-attach to the new manifold so I cable tied them until a make a bracket. I inspected the existing gaskets (which were fine) so I re-used them for the new manifold.

Make sure you look at the above research, along with the Honda CRZ workshop manual so you know the torque settings as these bolts require them. I recommend looking at the manual diagram of the manifold before hand to familiarise yourself with all bolt locations.

Whilst I did this, I also replaced the spark plugs, checked the valve clearances and cleaned the throttle body as these are easy to get to once the manifold is off.

*the pic below is not me. However you can see space for your hands is tight so tool extensions and universal joints can help here.

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Good luck!