Skaterift comes with the addon in its game files, we just need to install
it. This addon script gets updated between skaterift versions. Here are the
steps to install it into Blender:
Go to edit>preferences, and open the addons section.
Press the install... button at the top right, and browse to the
Skaterift game files. Inside the folder named tools is the script
blender_export.py to install.
If you don't know where it is, you can go into your Steam Library, and
rightclick Skaterift, selecting Manage>Browse local files.
Now search for Skaterift .mdl exporter from the addons list, and enable
it.