installing NLTK

[Nige Danton]

Mac OSX python 2.6.1: I'm trying to install the natural language toolkit
and following the instructions here www.NLTK.org/download I've downloaded
the PyYAML package and in a terminal window tried to install it. However
terminal asks for my password - I've tried both my user password and admin
password but neither is accepted. What am I doing wrong?

Thanks for any help

-- 
Nige Danton - Replace the obvious with g.m.a.i.l