Searching Proxy Switcher

Hi,

i search a proxy switcher that can handle private proxies with user/password activation.
Other things:
1. The tool should swicht a proxy from a list after x seconds.
2. The tool should rute the hole internet traffic over proxies so that a config of a browser is not needed.
3. i want use it with proxies from the sales thread in BHW
Any ideas to a good tool?

Regards
Herbert