Mel - I'd try a small cup, the smaller the better. When I was cup feeding, Oscar was tiny so we mainly used a medicine measuring cup, but I think if you get one of those baby food storage type plastic cups you could do it. I certainly was able to feed him a bit of EBM from an Avent storage cup (carries 200mls of liquid) and that should be a perfect size. Oscar is discovering his fingers and other objects to suck on, but I'm not convinced it's to do with teething. He is watching us eat, but I'm not convinced it means he's ready to start solids (not that I was going to before 6 months, anyway), either.
I'm toying with my ticker ATM, so don't panic - I'll have a photo up soon!