Using a proxy to grab XMLTV data with mythfilldatabase
Firstly, verify that the following command works (ie, fetches guide data and fills up your database) with your tv_grab_xxx script:
Replace <proxy> and <port> with the appropriate values. If it doesn't work you should verify that you have configured your grabber correctly and set mythtv to use it with mythtv-setup.
Once you have got that working, set up a cron job that runs daily by putting the following in /etc/cron.daily/mythtv-backend (or similar):
#!/bin/sh su mythtv -c "http_proxy=http://<proxy>:<port> mythfilldatabase --quiet"
This also assumes that 'mythtv' is the name user that should run mythfilldatabase (ie, has the configuration for tv_grab_xxx and ~/.mythtv/mysql.txt in place). Replace 'mythtv' above if you use another username.
Using a proxy server with MythBrowser, MythNews, MythWeather and so on
As far as I am aware this is presently unsupported. There is a feature request for this on this page