AFAIK this is usually done using body groups, these models don't have any as I see. But I could be wrong.
cat_clock has an amimation of moving cat's eyes.

What you can do is decompile the model and edit it in Blender for example then compile your result into a new model. But I'm not aware if there is a decompiler for Source 2 models. Crowbar decompiler works well for Source 1.

hello,

you can put the clock model in your map as a prop_static. then right click the clock model and convert it to a editable mesh. right click opens up a dropdown menue. i think the top entry "model under mouse" has the conversion option in it. have a look and experiment with it.

you can then select faces with the faces tool. the same tool you use to select faces on your brush walls.

when you use the faces selection tool you can extract faces that separates them from the original mesh.

i try to show or explain it better later but i dont have the game installed at the moment.