The installation instructions are on this page.[steamreview.org].

Did you check the box in the addons list?

The maximum length of a Blender datablock name is 63 bytes of UTF-8, so it's Blender itself doing the trimming.

That also means that it's going to be a pain to import those very long material names properly as Python strings deal with characters, not bytes.

The solution I'm currently in favour of is detecting the common directory at the start of each material name and removing it, which makes Crowbar putting it in a bit pointless. :) Could you possibly stick the common directory into the QC as $cdmaterials instead?

Please upload the file you're trying to import.

Select your object then go into weight painting mode[www.blender.org] and remove the weight.

Don't unzip the file. Just give it to Blender as Freddie described.

Source doesn't support unicode material names, so you'll need to change them regardless. I'll replace the error with a warning on export.

You can double-click on each item to change its name. You can also turn on international fonts in Prefs > System to see the characters properly

However, Unicode material should either be supported or produce a friendlier error message. I'll look into fixing that.

https://developer.valvesoftware.com/wiki/Blender_Source_Tools_Help#Exporting

Irises are rendered in Source using a special shader. I'm surprised you have anything at all there, normally it would be blank. Presumably you're seeing placeholder stuff from the texture?

What is the head parented to?