AND NOW TO MAKE THIS TOPIC LESS OF A CHEAP SOURCE OF HYPE, AND MORE OF A LEGITIMATE DISCUSSION!
My solution to the riddle:
Launch a projectile across the room, next to the cake. Upon contact with the wall the projectile spawns two missile objects on either side. The missiles will, on destruction (Contact with a wall) use A_RemoteAction to rotate the original projectile, and cause it to spawn more of the side-missiles. The missiles will of course fade after so long. Within a short period of time, the portal will be rotated to match the wall's angle.
A similar object, though technically a different type, will be launched to the player's side of the room, doing all the same stuff. The player will be followed by an object that constantly points itself towards the projectile at the far room. When the player touches the portal, he is A_RemoteActioned over to the other one, and turns to face the same angle as the the object that had moments ago, been pointing towards the portal he is now standing right in front of.
As I said, it's just a theory, and my angle trick with the object following the player doesn't sound like it'll really work, but I know the secret to getting it to work does involve that thing somehow.
Guess what I'm talking about yet? If not, read it again until your head explode.
Now we've got the cake, but that's not quite the weapon I'm looking for yet. Hence the turn of this topic to a more legit discussion. I require assistance getting the angle shifting to work like it does in the original game. Now I know I won't be able to do the fancy infinite loop to terminal velocity bit with portals on floors and ceilings, but at least the proper tricks for walls. Any ideas on how this issue could be resolved?