I have an apple computer running Leopard with python 2.6. I downloaded the latest version of scapy and ran \"python setup.py install
\". All went according to plan
I've also had lots of issues getting Scapy and its dependencies properly installed on my Mac, finally I found Homebrew Python GitHub page https://github.com/Homebrew/homebrew-python it contains lots of helpful/useful brew formula including one for Scapy that worked like a charm for me.
brew tap Homebrew/python
brew install scapy
I also had an issue with my pcapy which was solved by another formula in the repo for pypcap, so same procedure.
brew install pypcap