Strange.. Are you sure you are using Python 2.7? Maybe both are installed on the machine but the 2.6 one is on your PATH variable, so whenever you simply type e.g. python manage.py install it uses the 2.6 one.
Anyway, about virtualenv, you should only need something like:
easy_install virtualenv
cd path/where/you/want/to/install/askbot
virtualenv .
That should be all. After this step, you will have your project folder (say askbot_project) and next to it, a folder bin where all the necessary tools have been installed.
@Pepe, @zaf is right you don't have permission to write to directory under
Evgeny ( 2012-05-20 22:03:10 -0500 )edit/usr/. Usevirtualenvtool and create the environment in the directory where you do have write permissions - anywhere in your user account will work.