Please note that everytime a Dota 2 update is released you will need to re-apply your mods in order for them to work.
I recommend doing this every time when you download some mods
1) Close Dota 2 (You don't have to shut down Steam)
2) Double Click on Install.exe
3) A window will appear which shows the files being patched autonomously, once you see "SUCCESS" in big green letters you may close the window.
5) if the exe shuts down immediately like this,
it means your dota 2 is not in the same place when steam is.
Enabling VPK Overriding
If you have already activated vpk overriding you can skip this part.
1) Right click the Steam tray icon to the bottom right of your desktop and click Library.
2) Right click on Dota 2 and select Properties
3) Now click on 'Set Launch Options'
4) Type "-override_vpk" into the field.
Installing a mod
This video help little bit
1) Copy all the folders of the mod you wish to use (f.x models, etc)
2) Navigate to .../steam/steamapps/common/dota 2 beta/dota/
3) Paste the folders into the above path.
4) If you wish to remove a mod, navigate to ../steam/steamapps/common/dota 2 beta/dota/ and delete files you've pasted.
It is a little bit broken, Also some of the particle effect mods does not work at all