Is it possible to create a script that would prevent the player from being able to save in combat? I know you can use the function IsInCombat to check if they are in combat, but is there a way to prevent the player from saving the game?

Hmm... I unfortunately cannot give you a complete answer, but I would imagine that no, you cannot, because I would think that they made it so you cannot do so to prevent errors and so forth -- I would think saving during combat would be a very unstable thing to do.

I must add that I am not a great reference for the GECK, but I do know some things.