No, AFAIK you can use any aero equipment you want; there is only one rule: no freewheels.

I'm going to be on my NJS bike, so track drops will have to do as the only bullhorns I have are a 26mm clamp. But I think as long as I stay in the drops, I will be relatively aero. I will be using my road clipless and wearing a kit, and I might be able to borrow my friend's TT helmet.

Right now I have a 49t chainring, so I'm thinking a 14t cog would be good. I would have to buy it, though. I do have a 13t cog, but do you guys think 49/13 would be TOO big? I've never ran a gear that large on my FG...