Yep, you need to use a
point_camera, which doesn't work at all in TF2. It isn't possible except for modifying the code of the game directly, which is practically impossible unless you have the source code (which isn't publicly available for TF2).
Open Fortress is a mod which allegedly fixes the issue, but it's pretty different from actual TF2. I'd suggest to head there if you're dead set on using it in your map, otherwise I'd just continue without them. You could kinda get away with something similar by using a custom animated texture, but it wouldn't accurately update to show changes.