How to use camrea changer script

i need to change the active camera for animation but idk how to use scripts how to get them use them or anything if someone could help i would be much abliged

http://blenderartists.org/forum/showthread.php?t=78775
http://blenderartists.org/forum/showthread.php?t=68341

Search the Tutorials forum, there may be more than the two above.

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