First, you will need to download these files:
https://www.dropbox.com/s/um1z30q9s62c96t/scout_halloweenjacket.mdl
Spooky Sleeves .dx90[www.dropbox.com]
https://www.dropbox.com/s/shoaexd0vxtrg6j/scout_halloweenjacket.vvd

It's simply a recompiled Spooky Sleeves model with the $hboxset variable commented out in the QC file. I'm new to modeling, so I included all three files in case there is a dependency I'm not aware of.

Place the files in:
“\steam\steamapps\common\SourceFilmmaker\game\usermod\models\player\items\scout”
If you are missing any of those folders, create them. The path should look like this:
http://i.imgur.com/iv2rpn8.jpg

Then start up SFM and add the model to the scene. No need to navigate to it manually. Just type in jacket in the search bar. If you are presented with two options for scout_halloweenjacket.mdl, choose the usermod one. That's the repaired one.

If everything was done correctly, you should be seeing the Spooky Sleeves model from any angle. I think the only time it doesn't show up is if the camera is in a wall, but theoretically, the camera shouldn't be in the wall :P

The main credit goes to Pte Jack and R234.
Pte Jack brought up the camera issue a few months ago and subsequently fixed his own item. R234 was the individual who said that the Spooky Sleeves had the same problem.
Camera Issue Thread

The majority of the rest of the credit goes to various FacePunch threads and Steam Community discussion threads. It was through these resources that I determined what to fix the model with and how to fix it with that tool (Blender).

I take no credit for the creation of the original model. I simply fixed a variable to allow for easier use in Source Filmmaker.

I hope this was of some use!