Using Flask in a virtual env on Python 2.6 mod_wsgi on RHEL 5.7. python26-mod_wsgi is part of EPEL.

appname.wsgi

# -*- coding: utf-8 -*-

import os
import sys
import site
import logging

site.addsitedir('/path/to/venv/lib/python2.6/site-packages')
sys.path.append('/path/to/venv')
sys.path.append('/path/to/venv/appname')

activate_this = '/path/to/venv/bin/activate_this.py'
execfile(activate_this, dict(__file__=activate_this))

from appname import app as application

dirlist.txt

Directory structure:

/path/to/venv/
    lib/python2.6/site-packages/
    bin/activate_this.py
    appname.wsgi
    appname/
        __init__.py
        [other modules for appname]

python26-mod_wsgi.conf

# Location: /etc/httpd/conf.d/python26-mod_wsgi.conf
#################################################################################
# mod_python and mod_wsgi compatibility note
#################################################################################
# mod_wsgi will deadlock if run in daemon mode while mod_python is enabled
# do not enable both mod_python and mod_wsgi if you are going to use the
# WSGIDaemonProcess directive
# In previous version of mod_wsgi, apache would segfault when both mod_wsgi
# and mod_python were enabled.  This update does not guarantee that will not
# happen.
#
#################################################################################
# Do not enable mod_python and mod_wsgi in the same apache process.
#################################################################################
#

# NOTE: By default python26-mod_python with not load if mod_wsgi is installed
# and enabled.  Only load if mod_python and mod_wsgi are not already loaded.

<IfModule !python_module>
    <IfModule !wsgi_module>
        LoadModule wsgi_module modules/python26-mod_wsgi.so
        WSGISocketPrefix /path/to/appname_root/ ### Should be owned by apache:apache
    </IfModule>
</IfModule>

vhost.conf

# Location: /etc/httpd/vhosts.d/vhost.conf
<VirtualHost vhost.company.com:80>
    ServerAdmin [email protected]
    ServerName vhost.company.com
    ServerAlias vhost

    WSGIDaemonProcess appname user=app_user group=app_group threads=5
    WSGIScriptAlias / /path/to/venv/appname.wsgi
    <Directory /path/to/appname_root/>
        WSGIProcessGroup appname
        WSGIApplicationGroup %{GLOBAL}
        Order deny,allow
        Allow from all
    </Directory>
</VirtualHost>