how do you install the first person mod for Grand Theft Auto IV: The Complete Edition?

[GI1TcH!mg G@M3R]

i have been trying to install this mod for more than 3 years and cannot get it working
i have all the files it needs for it to work, I also downgraded, searched for any files that i missed but still nothing wtf is going on??

[xentus]

https://www.youtube.com/watch?v=SCT5PEEW14k&t=0s

[GI1TcH!mg G@M3R]

I tried to install the mod menu but
- i didn't know how to open the menu
- or i didn't know how to install it correctly

(yes i know it incluses First Person)
but how do you install it? and do you need to downgrade gta 4 to get it working?