Just animate only the portal in the some animation frames or add bone to the center of the portal, attach vertices to it, name the bone and use ent_bonerotate to rotate it around the angles you want.
Thank you Reconnoiter. I ended up just doing without the frame, but your post is making me think about putting it back in, for it sounds like it will work. I will try it, and let you know how it goes. Thank you.
