Using a search engine (API) to retrieve user generated content

Hi,

for a new project I am trying to retrieve user opinions from the web with search engines. A good way I found is using google and searching only in "discussions". I tried to use the google custom search api to search only in discussions without success. It seems that there is no parameter to tell google to search only in discussions with the given api.

The other big search engines (bing, yahoo, duckduckgo, blekko) doesn't offer searching in discussions only.

This is why I registered here. Can anyone recommend a service (paid or free) for querying google by using proxies and other techniques to prevent googles bot detection?

Thanks
jim