Is there a way to make first person cut-scenes in Halo CE or Halo 1? How about first person vehicles?

Yes.

There's a tickbox in Guerrilla for first-person view when you're in a vehicle, I believe, but first-person cutscenes would require animating a set of third-person arms and/or legs and synchronizing camera movement in such a way that everything appears to be connected. I don't think that you can attach a cutscene camera to a first-person model.

http://www.halomods.com/ips/index.php?/topic/680-cmts-the-silent-cartographer-evolved-media-month-the-month-is-now-over/page__st__40__p__8201#entry8201

Scroll down a bit.

Has anyone attempted to do this before?

I have.
It works, you just need a custom animation for the camera, make the fp arms a scenery then create a custom animation for those arms!

Here is a scenery with bones.
http://youtu.be/FEmWVXL_eHg
Now that isn't an elite biped there, its an elite scenery with bones!

This would mean that FP models would animate as scenery properly, which means custom animations would work on it, which means you can animate a camera to be in place of the arms, which means a FP cutscenes!

I noticed your Heretic Hunt project trailer and saw it had first person cut-scenes. It looks good btw. Changing the subject to vehicles; how would I create a first person view in vehicles?

I would think it is just moving the camera marker in 3ds max.
I have not tried this.

Someone mentioned editing this in Guerilla. The only thing I could find was to un-check the third person view box but it didn't do anything.

You also have to check the box "allows weapons".

I've also successfully implemented FP Cutscenes into my project OSS from CE3. So long as you know how to orient the camera, you can constrain it to a bone and everything should work out from there

So would it actually be first person driving or is it just a normal view with a weapon inside of the vehicle?

Alright.