"But like I said before you need to make them infantry units (which will require some reanimating), which sucks because even if they are huge, the game still treats them as small and they act and react as such. Meaning they react to every little hit and would be useless so large. Better of just keeping them mounts if you want them to be big."
Well I did say you could do it if you want to redo the animations for the models...
As long as ANY model has the general animations it should work, you can even give mounts this animation, but they just stand there in battle. But there is the "hit" problem with infantry class units. Every time someone hits them (which due to there size and radius will be far more often) the unit stumbles or something (because they are infantry), meaning they will be taking hits constantly (stumbling) and never giving them. Did you try fighting the whole battle to see how it works out? So basically they will be high hit point punching bags I think, but I am not sure.
But Glaurung has to be a mount general as he definitely won't work as infantry, plus he has a ranged attack so that will cause a CTD. But I think he should be a one man unit with no bodyguard anyway.