Hi Rebekah,
I'm not on my computer so don't have Crysis up in front of me, but you
could get a tag point- found under the AI tab in the roll up bar I
think- and set its axis as the axis you want, then link your model to
it. Remember the parent child link process is: have the child selected
first (your model as a brush or entity), and link it to the parent
(the tag point).
Instead if using a tag point, you could also just use a blank entity-
get a physics entity, line its axis up where you want it and just
don't assign a model to it. Hope this helps.