Hi,
You should look at this script: http://google-scraper.squabbel.com/
It's an open source PHP based multi-page multi-keyword google scraper that has the seo-proxies API fully integrated.
You can take the API functions out in case you write in PHP, otherwise they show how to use the API profesisonally.
The simple approach is to just blindly open the API URL passing your id,key and "rotate" as command. It will change your proxy external IP within about one second.