Did this and thought I'd post how I did it incase anyone else is interested. Mine isn't perfect but I'll probably fix it at some point.

Tools needed:
~44m holesaw
Some scrap wood
Glue of some sort
Sandpaper
Dremel is helpful
Sidecutters

Start by taking your gauge apart and glue it back together with the original screws (just add some hot glue to the tip of the screw and push it through this will hold the gauge together just fine):




Next take some scrap wood and drill a ~44m plug out of it to act as a drill guide. Might have to sand a bit to make it fit perfectly:


Using the same hole saw carefully cut a hole into the cluster face(as you can see mine slipped a bit but that's okay):




Next cut a piece off the other side and try to make the other gauge bezels as thin as possible:



Check fitment of the gauge:



With sandpaper/utility knife/dremel keep sanding the hole bigger and the other bezels thinner:



For best results try to sand down and right/away from the other bezels as it is a quite tight fit.

Once you're satisfied with your gauge placement just glue it down:



For the housing modifications just delete everything here with the weapon of your choice:



If you don't want to damage the circuit board then just chomp a hole to the side and you can easily snake the wires through there:



otherwise you can just cut some channels in the board without damaging any of the circuitry.

Optional:

You can add some tiny pegs to access the buttons which is kinda useless:



Mine are just some small drill bits cut to length for now. Once I get some extra sticks that are normally used in gauge clusters I'll drill bigger holes and use those.

and finished cluster:


(the button pegs aren't glued in this picture so they're just flopping around)

as you can see mine came out a bit oval and it's not quite fully visible on the right side, just take more care when sanding and it'll fit fine. When I have more time I'll tweak it and get it perfect. Moving it down a bit will give you a bit more room to make it perfectly round and completely visible.

Using a bit bigger than 44mm holesaw would probably end up better.
Anyways I just wanted it there in my face for now :3

For the wiring you can tap into the ignition wiring if you don't have any power source already.
The 2 midsize wires are for acc(blue/yellow for me) and on(blue/black for me) of course check them with a multimeter first.

and one more picture of it in the car